Overview

Brief Summary

Pussy willow is highly variable in its identifying characteristics. Typically it grows as a shrub or small tree to heights of up to 30 feet (8 m) [42]. Willows, in general, grow rapidly and produce extensive root systems [19]. Pussy willow trunks may be single or clustered with stout ascending branches and branchlets [16,42,80]. A large trunk circumference of 61.8 inches (157 cm) was reported for a North American pussy willow (Hightshoe cited in [81]). Bark is slightly fissured and ridged [80]. First-year pussy willow twigs are hairy but become glabrous with age [23,92]. Twigs are flexible and average 1.5 mm in diameter [80]. Large buds (up to 1 cm long) are present and conspicuous along the stems [36,84].

Pussy willow leaves are deciduous, simple, and alternate [16]. Leaf shape varies from oblong to elliptic, and blades are typically 2 to 5 times as long as they are wide [10,24,77]. Blade length varies from 1.2 to 5.1 inches (3-13 cm), and petioles measure 0.2 to 0.8 inch (5-20 mm) long [53,84]. Leaf margins are typically toothed, but the pattern is inconsistent [10,23,38]. Flowers occur in dense catkins. Catkin buds are covered in dense silky hairs and are the best known pussy willow feature [33]. Mature fruiting female catkins are typically 1 to 4.7 inches (2.5-12 cm) long, while mature fruiting male catkins measure 0.6 to 2 inches (1.5-5 cm) long [77]. Historic reports from an early beekeeper indicated that a single staminate pussy willow catkin contained 270 individual flowers and a pistillate catkin had 142 flowers [19]. Neither the age nor location of the catkin-providing shrub was reported. Pussy willow produces long-necked capsule fruits that measure 0.2 to 0.5 inch (5-13 mm) long [53,80]. Seeds are small (1.2-1.6 mm long and 0.5 mm in diameter) and have rings of short, stiff and long, silky hairs at the base [80].

Pussy willow is common throughout the southern half of Canada and the north-central and northeastern portions of the United States. The westernmost and southernmost distribution of pussy willow in the United States is not entirely clear [54]. There is general agreement that pussy willow occurs from Montana and Wyoming east through Illinois, Kentucky, and West Virginia [10,25,53,60,84]. However, Froiland [34] indicates that pussy willow occurs as far west as the Cascade Mountains of Oregon and Washington. Some researchers report pussy willow in Idaho [2,54], but these claims are not substantiated by floras from these areas. Some authors indicate that the southern US distribution includes Nebraska, eastern Tennessee, and western North Carolina [2,54]. The distribution of pussy willow varieties is not well described

  • 2. Argus, George W. 1957. The willows of Wyoming. University of Wyoming Publications in Science. Laramie, WY: University of Wyoming. 21(1): 1-63. [4962]
  • 10. Booth, W. E.; Wright, J. C. 1962. [Revised]. Flora of Montana: Part II--Dicotyledons. Bozeman, MT: Montana State College, Department of Botany and Bacteriology. 280 p. [47286]
  • 16. Chapman, William K.; Bessette, Alan E. 1990. Trees and shrubs of the Adirondacks. Utica, NY: North Country Books, Inc. 131 p. [12766]
  • 19. Dalby, Richard. 1999. Willows are wonderful. American Bee Journal. 139(3): 220-221. [67517]
  • 23. Dorn, Robert D. 1977. Flora of the Black Hills. Cheyenne, WY: Robert D. Dorn and Jane L. Dorn. 377 p. [820]
  • 24. Dorn, Robert D. 1984. Vascular plants of Montana. Cheyenne, WY: Mountain West Publishing. 276 p. [819]
  • 25. Dorn, Robert D. 1988. Vascular plants of Wyoming. Cheyenne, WY: Mountain West Publishing. 340 p. [6129]
  • 33. Farrar, John Laird. 1995. Trees of the northern United States and Canada. Ames, IA: Blackwell Publishing. 502 p. [60614]
  • 34. Froiland, Sven G. 1962. The genus Salix (willows) in the Black Hills of South Dakota. Technical Bulletin No. 1269. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 75 p. [5992]
  • 36. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York: New York Botanical Garden. 910 p. [20329]
  • 38. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]
  • 42. Hewsholme, Christopher. 1992. Willows: The genus Salix. Portland, OR: Timber Press, Inc. 224 p. [20106]
  • 53. Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer). Available: http://www.npwrc.usgs.gov/resource/plants/vascplnt/vascplnt.htm [2006, February 11]. [22534]
  • 54. Little, Elbert L., Jr. 1977. Atlas of United States trees. Volume 4. Minor eastern hardwoods. Misc. Pub. No. 1342. Washington, DC: U.S. Department of Agriculture, Forest Service. 17 p. [21683]
  • 60. Mohlenbrock, Robert H. 1986. [Revised edition]. Guide to the vascular flora of Illinois. Carbondale, IL: Southern Illinois University Press. 507 p. [17383]
  • 77. Seymour, Frank Conkling. 1982. The flora of New England. 2nd ed. Phytologia Memoirs 5. Plainfield, NJ: Harold N. Moldenke and Alma L. Moldenke. 611 p. [7604]
  • 80. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
  • 81. Stevens, George C.; Perkins, Anjeanette L. 1992. The branching habits and life history of woody plants. The American Naturalist. 139(2): 267-275. [17983]
  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
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Comprehensive Description

Comments

This shrub should not be confused with the non-native Salix caprea (Goat Willow). This latter species is often cultivated and it is also called 'Pussy Willow.' The Goat Willow has even larger male catkins than the native Pussy Willow, but it rarely escapes into the wild. While it is rather variable across its range, the native Pussy Willow can be distinguished from other similar willows by its leaves
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Description

This native shrub is about 6-20' tall, forming single or multiple trunks. Most branches are erect to ascending and little-branched. An older shrub forms a gray-brown bark near the base that is slightly rough and fissured, while the bark of upper branches and twigs is reddish brown to brown and smooth. Actively growing stems are yellowish green to light green and either smooth, slightly pubescent, or densely pubescent (rarely the latter). The alternate leaves of these stems are up to 4" long and 1½" across; they are ovate to narrowly ovate in shape and irregularly crenate-serrate to nearly smooth along their margins. The upper leaf surfaces are medium to dark green and hairless, while their lower surfaces are hairless, glaucous, and whitened. Shrubs with pubescent leaf undersides are probably hybrids. The slender petioles are up to ¾" long and usually slightly pubescent. At the base of some petioles (particularly for vigorously growing shoots), there is a pair of large stipules up to ¼" long and across; these stipules are somewhat cordate in shape and either crenate-serrate or deeply lobed. On second-year twigs, catkins of either male or female florets develop from sessile scales. Pussy Willow is dioecious, with either all male or all female florets on separate shrubs. As the male catkins begin to open, they are covered with dense hairs that are silky gray. Shortly later, they become larger in size (about 1" long) and yellowish in appearance from many stamens. Each male catkin consists of a dense mass of male florets; each floret has 2 stamens. The female catkins are spike-like racemes of female florets; these greenish catkins are 1-4" long at maturity. Each female floret consists of a pistil with a pair of tiny stigmata at its apex; the pistil is narrowly lanceoloid and canescent. The blooming period occurs from early to mid-spring for about 2 weeks. The female florets are replaced by seed capsules about 1/3" long. During the summer, these capsules split open to release tiny seeds with cottony hairs. These seeds are distributed by wind or water. The root system is woody and branching.
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Distribution

National Distribution

Canada

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

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Pussy willow is common throughout the southern half of Canada and the north-central and northeastern portions of the United States. The westernmost and southernmost distribution of pussy willow in the United States is not entirely clear [54]. There is general agreement that pussy willow occurs from Montana and Wyoming east through Illinois, Kentucky, and West Virginia [10,25,53,60,84]. However, Froiland [34] indicates that pussy willow occurs as far west as the Cascade Mountains of Oregon and Washington. Some researchers report pussy willow in Idaho [2,54], but these claims are not substantiated by floras from these areas. Some authors indicate that the southern US distribution includes Nebraska, eastern Tennessee, and western North Carolina [2,54]. The distribution of pussy willow varieties is not well described. The US Geological Survey provides a distributional map of pussy willow.
  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
  • 2. Argus, George W. 1957. The willows of Wyoming. University of Wyoming Publications in Science. Laramie, WY: University of Wyoming. 21(1): 1-63. [4962]
  • 25. Dorn, Robert D. 1988. Vascular plants of Wyoming. Cheyenne, WY: Mountain West Publishing. 340 p. [6129]
  • 34. Froiland, Sven G. 1962. The genus Salix (willows) in the Black Hills of South Dakota. Technical Bulletin No. 1269. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 75 p. [5992]
  • 54. Little, Elbert L., Jr. 1977. Atlas of United States trees. Volume 4. Minor eastern hardwoods. Misc. Pub. No. 1342. Washington, DC: U.S. Department of Agriculture, Forest Service. 17 p. [21683]
  • 60. Mohlenbrock, Robert H. 1986. [Revised edition]. Guide to the vascular flora of Illinois. Carbondale, IL: Southern Illinois University Press. 507 p. [17383]
  • 10. Booth, W. E.; Wright, J. C. 1962. [Revised]. Flora of Montana: Part II--Dicotyledons. Bozeman, MT: Montana State College, Department of Botany and Bacteriology. 280 p. [47286]
  • 53. Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer). Available: http://www.npwrc.usgs.gov/resource/plants/vascplnt/vascplnt.htm [2006, February 11]. [22534]

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USA: CT , DE , IL , IN , IA , KY , ME , MD , MA , MI , MN , MO , MT , NH , NJ , NY , NC , ND , OH , PA , RI , SD , VT , VA , WV , WI , WY (NPIN, 2007)

Canada: AB , MB , NB , NL , NT , NS , ON , PE , QC , SK , YT (NPIN, 2007)

Native Distribution: Nf. to B.C., s. to VA, KY, n. WY & c. ID (NPIN, 2007)

USDA Native Status: L48(N), CAN(N) (NPIN, 2007)

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Physical Description

Morphology

Description

More info for the terms: capsule, natural, shrub, shrubs, tree

This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available (e.g., [10,23,24,38,92]).

Pussy willow is highly variable in its identifying characteristics. Typically it grows as a shrub or small tree to heights of up to 30 feet (8 m) [42]. Willows, in general, grow rapidly and produce extensive root systems [19]. Pussy willow trunks may be single or clustered with stout ascending branches and branchlets [16,42,80]. A large trunk circumference of 61.8 inches (157 cm) was reported for a North American pussy willow (Hightshoe cited in [81]). Bark is slightly fissured and ridged [80]. First-year pussy willow twigs are hairy but become glabrous with age [23,92]. Twigs are flexible and average 1.5 mm in diameter [80]. Large buds (up to 1 cm long) are present and conspicuous along the stems [36,84].

Pussy willow leaves are deciduous, simple, and alternate [16]. Leaf shape varies from oblong to elliptic, and blades are typically 2 to 5 times as long as they are wide [10,24,77]. Blade length varies from 1.2 to 5.1 inches (3-13 cm), and petioles measure 0.2 to 0.8 inch (5-20 mm) long [53,84]. Leaf margins are typically toothed, but the pattern is inconsistent [10,23,38]. Flowers occur in dense catkins. Catkin buds are covered in dense silky hairs and are the best known pussy willow feature [33]. Mature fruiting female catkins are typically 1 to 4.7 inches (2.5-12 cm) long, while mature fruiting male catkins measure 0.6 to 2 inches (1.5-5 cm) long [77]. Historic reports from an early beekeeper indicated that a single staminate pussy willow catkin contained 270 individual flowers and a pistillate catkin had 142 flowers [19]. Neither the age nor location of the catkin-providing shrub was reported. Pussy willow produces long-necked capsule fruits that measure 0.2 to 0.5 inch (5-13 mm) long [53,80]. Seeds are small (1.2-1.6 mm long and 0.5 mm in diameter) and have rings of short, stiff and long, silky hairs at the base [80].

The following floras provide specific, local information useful for distinguishing pussy willow from similar looking sympatric species [16,77,92]. For systematic information on pussy willow varieties, see Braun [11] and Seymour [77].

Hybrids: Pussy willow has been described as freely hybridizing [92]; however, many barriers to natural hybridization such as flowering date, pollination and seed incompatibility, inviable seedling production, and reduced fertility are reported for many potential pussy willow hybrids [3,63,64,65]. It is possible that the highly variable nature of pussy willow shrubs has been erroneously attributed to hybridization.

  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
  • 36. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York: New York Botanical Garden. 910 p. [20329]
  • 92. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472]
  • 3. Argus, George W. 1974. An experimental study of hybridization and pollination in Salix (willow). Canadian Journal of Botany. 52(7): 1613-1619. [67515]
  • 11. Braun, E. Lucy. 1961. The woody plants of Ohio. Columbus, OH: Ohio State University Press. 362 p. [12914]
  • 16. Chapman, William K.; Bessette, Alan E. 1990. Trees and shrubs of the Adirondacks. Utica, NY: North Country Books, Inc. 131 p. [12766]
  • 19. Dalby, Richard. 1999. Willows are wonderful. American Bee Journal. 139(3): 220-221. [67517]
  • 23. Dorn, Robert D. 1977. Flora of the Black Hills. Cheyenne, WY: Robert D. Dorn and Jane L. Dorn. 377 p. [820]
  • 24. Dorn, Robert D. 1984. Vascular plants of Montana. Cheyenne, WY: Mountain West Publishing. 276 p. [819]
  • 33. Farrar, John Laird. 1995. Trees of the northern United States and Canada. Ames, IA: Blackwell Publishing. 502 p. [60614]
  • 38. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]
  • 42. Hewsholme, Christopher. 1992. Willows: The genus Salix. Portland, OR: Timber Press, Inc. 224 p. [20106]
  • 63. Mosseler, A. 1989. Interspecific pollen-pistil incongruity in Salix. Canadian Journal of Forest Research. 19: 1161-1168. [9348]
  • 64. Mosseler, A. 1990. Hybrid performance and species crossability relationships in willows. Canadian Journal of Botany. 68(11): 2329-2338. [60064]
  • 65. Mosseler, A.; Papadopol, C. S. 1989. Seasonal isolation as a reproductive barrier among sympatric Salix species. Canadian Journal of Botany. 67: 2563-2570. [10066]
  • 77. Seymour, Frank Conkling. 1982. The flora of New England. 2nd ed. Phytologia Memoirs 5. Plainfield, NJ: Harold N. Moldenke and Alma L. Moldenke. 611 p. [7604]
  • 80. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
  • 81. Stevens, George C.; Perkins, Anjeanette L. 1992. The branching habits and life history of woody plants. The American Naturalist. 139(2): 267-275. [17983]
  • 10. Booth, W. E.; Wright, J. C. 1962. [Revised]. Flora of Montana: Part II--Dicotyledons. Bozeman, MT: Montana State College, Department of Botany and Bacteriology. 280 p. [47286]
  • 53. Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer). Available: http://www.npwrc.usgs.gov/resource/plants/vascplnt/vascplnt.htm [2006, February 11]. [22534]

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Overall this is a shrub or rarely a small tree. (Peattie, 1930) Only occasionally reaches bushy tree size. (Weeks et al, 2005) This is a narrow shrub or small tree. This is a many-stemmed shrub or small tree with an open rounded crown. (NPIN, 2007)

Flowers The sexes are on different plants. Male flowers are accompanied by 1 or 2 small glands. Female flowers have a small flat gland near the base of the ovary. Each flower is subtended by a scale. Flowers appear before the leaves. Catkins are stout and dense. The male catkins are particularly handsome. Scales are brown or black. There are 2 stamens with stigmas equalling the styles. (Peattie, 1930)The familiar, silvery-gray, furry catkins appear before leaf emergence. The silky, furry catkins appear in late winter and early spring. The large flower buds burst and expose their soft silky hair, or pussy fur, early in the year. Some twigs will produce beautiful golden stamens, while others will bear slender greenish pistils. The bloom color is white, green, and/or brown. (NPIN, 2007) The catkin is mostly stalkless. (UW, 2009)

Fruit The capsules are conic, rostrate, and densely gray-woolly. (Peattie, 1930) Fruit color is brown. (NPIN, 2007)

Leaves Young leaves are much unlike the mature ones. Stipules are large and roundish. Mature leaves are short-lanceolate to elliptic-oblanceolate. They are glabrous (hairless) beneath and glaucous (with a bluish whitish coating). Leaves are dark and shining green above. The bases are acute, tips barely acute, and margins closely but irregularly crenate-serrate in the middle and subentire. (Peattie, 1930) Deciduous leaves are broad, bright-green and shiny. The Latin species name refers to the contrasting colors of the leaf surfaces, which aid in recognition. (NPIN, 2007) Leaves are mostly elliptic, edges are flat, leaves are usually shiny green above, and the underside is whitened. (UW, 2009)

Stems This plant has round and limber twigs. Twigs are stout and black or dark purple. (Peattie, 1930) Multiple trunks typify this plant. (NPIN, 2007)

Bark is smooth and reddish. (Peattie, 1930) Dark-gray, scaly bark is typical. (NPIN, 2007)

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Size

Plant is to 20' tall. (NPIN, 2007) Maximum height at 20 years is 20'. Height at maturity is 40.0'. (USDA PLANTS, 2009)

Flowers The catkins are 2-4 cm long, or finally 4-8 cm long. (Peattie, 1930) The buds are up to 1/3". Catkins are 1" long. (UW, 2009)

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Type Information

Syntype for Salix discolor var. overi C.R. Ball
Catalog Number: US 2440667
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): W. Over
Year Collected: 1922
Locality: Hiawatha Beach, Big Stone Lake., Roberts, South Dakota, United States, North America
  • Syntype: Ball, C. R. 1924. Rhodora. 26: 137.
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Syntype for Salix discolor var. overi C.R. Ball
Catalog Number: US 2440666
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): W. Over
Year Collected: 1922
Locality: Hiawatha Beach, Big Stone Lake., Roberts, South Dakota, United States, North America
  • Syntype: Ball, C. R. 1924. Rhodora. 26: 137.
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Syntype for Salix discolor var. overi C.R. Ball
Catalog Number: US 1285111
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Preparation: Pressed specimen
Collector(s): C. R. Ball & W. Over
Year Collected: 1923
Locality: Hiawatha Beach, Big Stone Lake., Roberts, South Dakota, United States, North America
  • Syntype: Ball, C. R. 1924. Rhodora. 26: 137.
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Look Alikes

Willows are a very difficult group to identify. This species is known by the marked contrast in color between the upper and lower leaf surfaces. (Peattie, 1930) The Latin species name refers to the contrasting colors of the leaf surfaces, which aid in recognition. Pussy willow catkins are the first willow catkins to appear each year. (NPIN, 2007)
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Ecology

Habitat

Habitat characteristics

More info for the terms: cover, litter, peat, shrub, swamp

Pussy willow occurs along waterways, shorelines, and swamp margins and in low-lying portions of poorly drained thickets, meadows, sloughs, and forest openings throughout its range [9,25,28,33,53,80].

Climate: Continental climates prevail in most of pussy willow's range, but climates in coastal habitats of the northeastern United States and southern Canada are likely moderated by maritime influences. It is difficult to summarize the entire range of climatic conditions experienced throughout pussy willow's range. The prevailing climates spanning a portion of pussy willow's distribution are summarized below.

In pussy willow habitats of northern Minnesota, rainfall averages 23 to 32 inches (580-810 mm)/year. More rain typically falls in the west than in the east. About 75% of the annual precipitation falls during the growing season from April to September. Winter often brings heavy snow. High and low temperatures of 104 °F (40 °C) and -76 °F (-60 °C), respectively, are reported in northern Minnesota [32]. In the Black Hills of South Dakota, where pussy willow occurs, winters are cold, and summers are warm. Annual precipitation averages 14 to 17 inches (360-430 mm) in the plains and up to 28 inches (710 mm) at high-elevation sites. Most precipitation (65-75%) occurs during the April to September growing season. More than 100 inches (2,500 mm) of snow may fall at high-elevation sites. A low temperature of -52 °F (-47 °C) is reported for the southern Black Hills, and a high of 112 °F (44 °C) is reported from Belle Fourche in the north. In the Black Hills, pussy willow was most common on north- or east-facing slopes [34]. In pussy willow habitats of the Inga Lake area of British Columbia, winters are long and cold with moderate snowpack, and summers are warm with frequent thunderstorms [39].

Elevation: Very few floras or other references report elevational distributions for pussy willow. It is described from 2,000 to 8,000 feet (600-2,000 m) in the Rocky Mountain region [26]. In the Black Hills of South Dakota, pussy willow is considered fairly common at elevations of 5,000 to 6,600 feet (1,500-2,000 m) [34]. In the Adirondacks, pussy willow occurs at 100 feet (30 m) elevation along Lake Champlain and at 2,878 feet (877 m) on Haystack Mountain; a pussy willow × Bebb willow hybrid occupies a site at 3,380 feet (1,030 m) on Noonmark Mountain [50].

Soils: Pussy willow is commonly found on poorly-drained soils with nearly neutral pH. Along Lake Champlain in the Adirondacks, pussy willow was common on poorly drained gneiss, anthracite, and limestone soils [50]. In a shrub-carr adjacent to White Clay Lake in Wisconsin, pussy willow cover was significantly greater on alluvial than histic surface soils (P<0.01). Available phosphorus and nitrogen were greatest in alluvial soils, and histic soil surfaces were covered with grasses and leaf litter [48]. Pussy willow was most common in very eutrophic (pH 7-7.9), wet (depth to water: 7.9-15 inches (20-39 cm)) peatlands near Candle Lake in central Saskatchewan, but also occurred in very moist (depth to water: up to 31 inches (79 cm)) peatlands with pH levels of 6 to 6.9 [47]. On the Saskatchewan River Delta, pussy willow occurs in low- and tall-shrub community types with shallow peat (1-3 feet (0.3-1 m)) over silty clay. These soils have a pH of 6.6 to 7 [20]. In the willow-alder tall shrub vegetation on rarely flooded levees of the Peace-Athabasca Delta, soils average 6.5 pH, 18% organic matter, and 82% mineral material of which 24% is sand, 49% is silt, and 27% is clay [21]. Pussy willow habitats in north-central British Columbia are on subxeric to subhydric, coarse to moderately fine soils [71].

Flooding tolerance: Along Midvale Creek in East Glacier, Montana, beaver dams created ponds and inundated riparian vegetation. Pussy willow was "thriving" after 5 years of inundation [1].

  • 1. Amlin, Nadine A.; Rood, Stewart B. 2001. Inundation tolerances of riparian willows and cottonwoods. Journal of the American Water Resources Association. 37(6): 1709-1720. [3600]
  • 9. Bird, Ralph D. 1961. Ecology of the aspen parkland of western Canada in relation to land use. Contribution No. 27. Ottawa: Canada Department of Agriculture, Research Branch. 153 p. [15620]
  • 20. Dirschl, H. J.; Coupland, R. T. 1972. Vegetation patterns and site relationships in the Saskatchewan River Delta. Canadian Journal of Botany. 50: 647-675. [7449]
  • 21. Dirschl, Herman J.; Dabbs, Don L.; Gentle, Garry C. 1974. Landscape classification and plant successional trends in the Peace-Athabasca Delta. Canadian Wildlife Service Report Series 30. Ottawa, ON: Canadian Wildlife Service. 33 p. [6177]
  • 25. Dorn, Robert D. 1988. Vascular plants of Wyoming. Cheyenne, WY: Mountain West Publishing. 340 p. [6129]
  • 26. Dorn, Robert D.; Dorn, Jane L. 1997. Rocky Mountain Region willow identification field guide. R2-RR-97-01. Denver, CO: U.S. Department of Agriculture, Forest Service, Renewable Resources. 107 p. [29146]
  • 28. Duncan, Wilbur H.; Duncan, Marion B. 1987. The Smithsonian guide to seaside plants of the Gulf and Atlantic coasts from Louisiana to Massachusetts, exclusive of lower peninsular Florida. Washington, DC: Smithsonian Institution Press. 409 p. [12906]
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 33. Farrar, John Laird. 1995. Trees of the northern United States and Canada. Ames, IA: Blackwell Publishing. 502 p. [60614]
  • 34. Froiland, Sven G. 1962. The genus Salix (willows) in the Black Hills of South Dakota. Technical Bulletin No. 1269. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 75 p. [5992]
  • 39. Haeussler, Sybille; Bedford, Lorne; Boateng, Jacob O.; MacKinnon, Andy. 1999. Plant community responses to mechanical site preparation in northern interior British Columbia. Canadian Journal of Forest Research. 29: 1084-1100. [38978]
  • 47. Jeglum, John K. 1971. Plant indicators of pH and water level in peatlands at Candle Lake, Saskatchewan. Canadian Journal of Botany. 49: 1661-1676. [7450]
  • 48. Johnston, Carol A. 2003. Shrub species as indicators of wetland sedimentation. Wetlands. 23(4): 911-920. [67520]
  • 50. Kudish, Michael. 1992. Adirondack upland flora: an ecological perspective. Saranac, NY: The Chauncy Press. 320 p. [19376]
  • 71. Porter, Glen L. 1990. Willow species of disturbed sites in the sub-boreal spruce zone in north-central British Columbia. FRDA Handbook 004; ISSN-0835-1929. Victoria, BC: Forestry Canada; B.C. Ministry of Forests. 67 p. [28015]
  • 80. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
  • 53. Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer). Available: http://www.npwrc.usgs.gov/resource/plants/vascplnt/vascplnt.htm [2006, February 11]. [22534]

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Key Plant Community Associations

More info for the terms: climax, fen, fern, peatland, shrub, swamp

The most typical pussy willow habitats include seral communities that dominate after the
colonization of open water by emergent vegetation and forests following canopy-opening
disturbance events. Pussy willow is shade intolerant, prefers moist site conditons, and rarely
persists beyond the water's edge in climax forest vegetation. Several seral
communities where pussy willow is a dominant are described below.

United States:



  • dogwood (Cornus spp.)-pussy willow-swamp rose (Rosa palustris)
    swamp shrublands in Minnesota

  • red-osier dogwood (C. sericea)-willow (Bebb willow, pussy willow,
    and meadow willow (Salix petiolaris))/slimstem reedgrass (Calamagrostis stricta)
    shrublands in Iowa, Minnesota, and North Dakota [76]

  • southern shrub-carr (tall shrub) vegetation types around lakes and ponds south of the
    tension zone in Wisconsin; pussy willow, other willows (Salix spp.), and red-osier
    dogwood are common dominants [18]
Canada:


Alberta:



  • willow-alder (Alnus spp.) tall shrub vegetation types on rarely flooded levees
    of the Peace-Athabasca Delta in northeastern Alberta; dominant species include pussy willow,
    Bebb willow, and thinleaf alder (A. incana subsp. tenuifolia) [21]

  • willow (including pussy willow)-bluejoint reedgrass (C. canadensis) vegetation
    is a hydrarch seral community in central Alberta [61]
Manitoba:

  • shrubby moderate-rich fen peatland types along lakes and streams on Duck
    Mountain [55]

  • pussy willow dominates the edge of quaking aspen (Populus tremuloides)-dominated
    deciduous forests of the Spruce Woods Forest and Game Reserve [8]

  • dogwood-pussy willow-swamp rose swamp shrublands

  • red-osier dogwood-willow (Bebb, pussy, and meadow willows)/slimstem reedgrass shrublands [76]
Quebec:

  • black ash (Fraxinus nigra)-pussy willow/sensitive fern (Onoclea sensibilis)
    community types on the shores of Lake Duparquet (Tardif and Bergeron as cited in [86])
Saskatchewan:

  • low willow (Pussy willow and meadow willow) shrub community types and tall willow-alder
    shrub community types dominated by speckled alder (Alnus incana subsp. rugosa)
    and pussy willow on the Saskatchewan River Delta [20]
  • 8. Bird, Ralph D. 1927. A preliminary ecological survey of the district surrounding the entomological station at Treesbank, Manitoba. Ecology. 8(2): 207-220. [63548]
  • 18. Curtis, John T. 1959. Tall shrub communities. In: Curtis, John T. The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press: 352-358. [60529]
  • 20. Dirschl, H. J.; Coupland, R. T. 1972. Vegetation patterns and site relationships in the Saskatchewan River Delta. Canadian Journal of Botany. 50: 647-675. [7449]
  • 21. Dirschl, Herman J.; Dabbs, Don L.; Gentle, Garry C. 1974. Landscape classification and plant successional trends in the Peace-Athabasca Delta. Canadian Wildlife Service Report Series 30. Ottawa, ON: Canadian Wildlife Service. 33 p. [6177]
  • 55. Locky, David A.; Bayley, Suzanne E.; Vitt, Dale H. 2005. The vegetational ecology of black spruce swamps, fens, and bogs in southern boreal Manitoba, Canada. Wetlands. 25(3): 564-582. [67524]
  • 61. Moss, E. H. 1932. The vegetation of Alberta: IV. The poplar association and related vegetation of central Alberta. The Journal of Ecology. 20(2): 380-415. [63588]
  • 86. Tardif, Jacques; Dery, Sephane; Bergeron, Yves. 1994. Sexual regeneration of black ash (Fraxinus nigra Marsh.) in a boreal floodplain. The American Midland Naturalist. 132(1): 124-135. [23927]
  • 76. Schneider, Rick E.; Faber-Langendoen, Don; Crawford, Rex C.; Weakley, Alan S. 1997. The status of biodiversity in the Great Plains: Great Plains vegetation classification. Supplemental Document 1. In: Ostlie, Wayne R.; Schneider, Rick E.; Aldrich, Janette Marie; Faust, Thomas M.; McKim, Robert L. B.; Chaplin, Stephen J., compilers. The status of biodiversity in the Great Plains, [Online]. Arlington, VA: The Nature Conservancy (Producer). 75 p. Available: http://conserveonline.org/docs/2005/02/greatplains_vegclass_97.pdf [2006, May 16]. On file with: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT. [62020]

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This plant prefers damp ground. (Peattie, 1930) Native habitat is marshy, low ground, stream banks, and ditches. (NPIN, 2007) Habitat is wet, swampy areas. (UW, 2009)
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Associations

Faunal Associations

The nectar and pollen of the florets attract mostly small bees and flies. Other insects that visit the florets to a lesser extent include honey bees and bumblebees, Ichneumon wasps, sawflies, butterflies, beetles, and plant bugs. The following oligolectic Andrenid bees have been observed visiting Pussy Willow
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© John Hilty

Source: Illinois Wildflowers

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Flower-Visiting Insects of Pussy Willow in Illinois

Salix discolor (Pussy Willow)
(bees suck nectar or collect pollen, flies suck nectar or feed on pollen, while other insects suck nectar; gender of inflorescence is unspecified; some observations of Andrenid bees are from Krombein et al., otherwise observations are from Graenicher)

Bees (long-tongued)
Apidae (Apinae): Apis mellifera sn cp (Gr); Apidae (Bombini): Bombus edwardii sn (Gr), Bombus griseocollis sn (Gr); Anthophoridae (Nomadini): Nomada integerrima sn (Gr); Anthophoridae (Xylocopini): Xylocopa virginica sn (Gr); Megachilidae (Osmiini): Osmia atriventris sn (Gr), Osmia lignaria lignaria sn (Gr)

Bees (short-tongued)
Halictidae (Halictinae): Agapostemon melliventris sn (Gr), Augochorella persimilis sn (Gr), Augochloropsis sumptuosa sn (Gr), Halictus sp. (Gr), Halictus confusus sn (Gr), Lasioglossum connexus sn (Gr); Halictidae (Sphecodini): Sphecodes dichroa sn (Gr); Colletidae (Colletinae): Colletes inaequalis sn (Gr); Andrenidae (Andreninae): Andrena andrenoides andrenoides sn cp olg (Gr), Andrena erigeniae sn (Gr), Andrena erythrogaster sn cp olg (Gr), Andrena forbesii sn (Kr, Gr), Andrena frigida (Kr), Andrena illinoiensis sn cp olg (Gr), Andrena imitatrix imitatrix (Kr), Andrena mandibularis sn (Gr), Andrena mariae sn cp olg (Gr), Andrena miserabilis bipunctata sn (Gr), Andrena rugosa sn (Gr), Andrena sigmundi cp olg (Kr), Andrena vicina sn (Gr)

Wasps
Braconidae: Casinaria eupitheciae sn (Gr); Ichneumonidae: Amblyteles sp. sn (Gr), Dolichomitus irritator sn (Gr), Glypta sp. sn (Gr), Glypta varipes sn (Gr), Lissonota parva sn (Gr), Scambus hispae sn (Gr); Vespidae (Polistinae): Polistes fuscata sn (Gr)

Sawflies
Tenthredinidae: Dolerus sericeus sn, Dolerus unicolor sn, Pontania spp. sn

Flies
Syrphidae: Brachypalpus cyanogaster sn/fp (Gr), Eristalinus aeneus sn/fp (Gr), Eristalis brousii sn/fp (Gr), Eristalis dimidiatus sn/fp (Gr), Eristalis tenax sn/fp (Gr), Eupeodes americanus sn/fp (Gr), Helophilus fasciatus sn/fp (Gr), Melanostoma mellinum sn/fp (Gr), Platycheirus obscurus sn/fp (Gr), Syritta pipiens sn/fp (Gr), Syrphus ribesii sn/fp (Gr), Toxomerus geminatus sn/fp (Gr), Toxomerus parvulus sn/fp (Gr); Conopidae: Myopa vicaria sn (Gr); Phoridae: Borophaga clavata sn/fp (Gr), Megaselia rufipes sn/fp (Gr); Tachinidae: Gonia capitata sn/fp (Gr), Siphona geniculata sn/fp (Gr), Tachinomyia panaetius sn/fp (Gr); Anthomyiidae: Delia platura sn/fp (Gr), Phorbia spp. sn/fp (Gr); Calliphoridae: Calliphora vicina sn/fp (Gr), Lucilia illustris sn/fp (Gr), Pollenia rudis sn/fp (Gr); Muscidae: Helina parsura sn/fp (Gr, 1900), Limnophora garrula sn/fp (Gr), Neomyia cornicina sn/fp (Gr); Sarcophagidae: Sarcophaga sarracenioides sn/fp (Gr); Ephydridae: Elachiptera nigriceps sn/fp (Gr), Ochthera mantis sn/fp (Gr); Sepsidae: Sepsis vicaria sn/fp (Gr); Piophilidae: Prochyliza xanthostoma sn/fp (Gr); Lonchaeidae: Lonchaea polita sn/fp (Gr); Scathophagidae: Scathophaga furcata sn/fp (Gr)

Butterflies
Nymphalidae: Nymphalis milberti sn (Gr), Vanessa atalanta sn (Gr)

Beetles
Chrysomelidae: Acalymma vittata sn (Gr); Coccinellidae: Adalia bipunctata sn (Gr); Curculionidae: Smicronyx corniculatus sn (Gr)

Plant Bugs
Lygaeidae: Unidentified sp. sn (Gr); Miridae: Adelphocoris superbus sn (Gr); Pyrrhocoridae: Dysdercus sp. sn (Gr)

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Known predators

Salix discolor is prey of:
Galerucella decora

Based on studies in:
Canada: Manitoba (Forest)

This list may not be complete but is based on published studies.
  • R. D. Bird, Biotic communities of the Aspen Parkland of central Canada, Ecology, 11:356-442, from p. 410 (1930).
  • R. D. Bird, Biotic communities of the Aspen Parkland of central Canada, Ecology, 11:356-442, from p. 393 (1930).
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© SPIRE project

Source: SPIRE

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Wildlife uses include early season harvest for songbirds, waterfowl and small mammals. The flowers attract butterflies. It is a larval host for Mourning Cloak (Nymphalis antiopa ) and Viceroy (Limenitis archippus). (NPIN, 2007)
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General Ecology

Fire Management Considerations

The above studies indicate that pussy willow is not adversely affected by fire. Repeated burning in pussy willow habitats will not likely remove this species. However, a lack of prefire or unburned comparisons makes predicting the effects of fire on pussy willow abundance difficult in most vegetation types. The gap in knowledge regarding pussy willow's postfire response on dry versus wet sites and in low-severity versus high-severity fires also makes postfire abundance predictions difficult. Additional and more detailed fire effects studies in pussy willow habitats are needed.

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Broad-scale Impacts of Plant Response to Fire

More info for the terms: climax, cover, density, fern, frequency, hardwood, peat, shrub, shrubs, tree

There are few fire effects studies on pussy willow. From the little information
available, the following generalizations can be made: pussy willow survives most
fires, postfire sprouts are often present by the first postfire year, and shrubs
regenerate and persist on repeatedly burned sites. Additional information
regarding effects of different fire seasons and fire severities on pussy willow are needed.
Comparisons of postfire sprouting and long-term survival on dry versus
wet burned sites would improve the understanding of pussy willow's response to
fire.
Several studies indicate that pussy willow is common in postfire communities
in the boreal forest; however, comparisons with unburned or prefire communities are
lacking. Pussy willow occurred in the shrub-dominated successional stage after fires
in black spruce swamps in Itasca County, Minnesota. There were 12 pussy willow clumps/100 m²
on sites visited 3 years after the last fire. Sites burned 2 to 3 times in 4 years.
Pussy willow was also noted in shrub-dominated postfire communities in red pine
(Pinus resinosa), jack pine (P. banksiana), highland hardwood, and
fir-birch (Betula spp.) forest types [37]. On 2-year-old burned sites
northwest of Ely, Minnesota, pussy willow was present. The boreal forest site burned
in the Little Sioux Fire in mid-May. Postfire abundance was not quantified, but willows
(pussy willow, Bebb willow, and sandbar willow (Salix interior)) were abundant
enough to provide 25% of local moose diets from April to December [45].
On a 2-year-old burned site on Moose Hill in southwestern Nova Scotia's
Queens County, the density of pussy willow was 0.5 individuals/6.6 × 6.6 foot
quadrat and frequency was 11%, respectively. The site was a regenerating
clearcut burned in late May and was dominated by eastern white pine and spruce that were about 8 feet
(2 m) tall. The burned site was flat and poorly drained with the water table at
about 19 inches (48 cm) deep [56]. In shrub and grassland alvars of eastern Ontario's
Burnt Lands, pussy willow frequency was 12%. Alvars were likely white spruce climax forests
that were cut and burned 37 years earlier [15].
Studies in the northern clay boreal forest of northern Ontario revealed that pussy willow
was associated with a group of species reaching their greatest abundance on 4- to 11-year-old
burned sites. Burned sites ranged from 0 to 57 years old. Through species classification
analyses, pussy willow was found to be correlated with the "dry peat" species group
on burned sites (P≤0.05). Researchers noted that most fires were "relatively
intense". Study findings did not address whether or not pussy willow or other dry peat
species were present or even somewhat abundant in younger and older postfire
communities [78].
Repeated fire: The following studies indicate
that pussy willow tolerates repeated burning. Pussy willow abundances were rarely very different
between repeatedly burned and unburned sites. There have been several fires and studies in
prairies and savannas of Wisconsin. Differences in the frequency of pussy willow between burned
and unburned sites were greatest on the most frequently burned sites. On sites burned 1 to 4
times in a 5- to 6-year period, pussy willow frequency was slightly lower on burned than unburned
sites [90]. In a brush savanna, pussy willow frequency was at least 25% greater on sites
burned 11 times in 15 years than on adjacent unburned sites. Fires consumed all foliage and
killed aboveground shrub and tree parts. Unburned reference sites had not burned for 35 years
or more [5].
In the Crex Meadow area of northwestern Wisconsin, pussy willow was 2.5% more frequent on
sites burned 1 to 4 times than on unburned sites. Pussy willow averaged 16.4% frequency on
unburned jack pine-northern pin oak (Quercus ellipsoidalis) brush prairie savannas that
had a partially closed canopy of 40% to 90% cover and were undisturbed for at least 25 years.
Frequency averaged slightly lower (13.9%) on 33 sites burned in prescribed fires. Sites were
typically burned 1 to 4 times in March or April. Burned sites averaged 1.9 fires and were
visited 1 to 2 years after the last fire [90,91].
The fire effect on pussy willow was considered "neutral" in western bracken fern
(Pteridium aquilinum)-grasslands in northeastern Wisconsin. The average frequency of
pussy willow was just 1.1% greater on burned than unburned sites. Fifteen burned stands and
12 adjacent unburned stands were compared. Fires burned in March or April, and all but 3 sites
burned once. The other 3 sites burned 2 to 3 times. Burned sites were evaluated the first
postfire summer. Unburned stands had not burned for 25 years or more [89].
  • 5. Beck, Alan M.; Vogl, Richard J. 1972. The effects of spring burning on rodent populations in a brush prairie savanna. Journal of Mammalogy. 53(2): 336-346. [196]
  • 15. Catling, Paul M.; Brownell, Vivian R. 1998. Importance of fire in alvar ecosystems--evidence from the Burnt Lands, eastern Ontario. The Canadian Field Naturalist. 112(4): 661-667. [30338]
  • 37. Grant, Martin L. 1929. The burn succession in Itasca County, Minnesota. Minneapolis, MN: University of Minnesota. 63 p. Thesis. [36527]
  • 45. Irwin, Larry L. 1985. Foods of moose, Alces alces, and white-tailed deer, Odocoileus virginianus, on a burn in boreal forest. The Canadian Field-Naturalist. 99(2): 240-245. [4513]
  • 56. Martin, J. Lynton. 1956. An ecological survey of burned-over forest land in southwestern Nova Scotia. Forestry Chronicle. 32: 313-336. [8932]
  • 78. Shafi, M. I.; Yarranton, G. A. 1973. Vegetational heterogeneity during a secondary (postfire) succession. Canadian Journal of Botany. 51: 73-90. [15191]
  • 89. Vogl, R. J. 1964. The effects of fire on the vegetational composition of bracken-grassland. Wisconsin Academy of Sciences, Arts and Letters. 53: 67-82. [9142]
  • 90. Vogl, Richard J. 1964. Vegetational history of Crex Meadows, a prairie savanna in northwestern Wisconsin. The American Midland Naturalist. 72(1): 157-175. [61264]
  • 91. Vogl, Richard John. 1961. The effects of fire on some upland vegetation types. Madison, WI: University of Wisconsin. 154 p. Dissertation. [52282]

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Plant Response to Fire

More info for the terms: cover, frequency

Basal sprouting is typical following fires that kill aboveground pussy willow stems [93]. Ewing reports that willows are top-killed by repeated prairie fires but sprout prolifically after fire [32]. Research indicates that pussy willow survives repeated fire. In a Wisconsin brush savanna, pussy willow frequency was greater on sites burned 11 times in 15 years than on adjacent sites unburned for 35 years or more [5]. Observations made in postfire seral communities in northwestern Minnesota suggest that fires on dry sites may be more damaging to pussy willow than fires in wet habitats. Pussy willow was typically most abundant and persistent in wet postfire communities. However, observations came from various sites with different levels of canopy cover, which also affected pussy willow abundance [32].

In the Waubun Prairie Research Area dominated by bluestem (Andropogon spp.), Indiangrass (Sorghastrum nutans), and porcupine grass (Hesperostipa spartea), pussy willow was top-killed by fire, and sprouts were present in the first postfire year. Portions of the Prairie were burned in spring and portions in the fall. It was unclear whether pussy willow occurred on spring, fall, or spring and fall burned sites. Pussy willow was restricted to wet soils and to pothole borders [87].

  • 5. Beck, Alan M.; Vogl, Richard J. 1972. The effects of spring burning on rodent populations in a brush prairie savanna. Journal of Mammalogy. 53(2): 336-346. [196]
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 87. Tester, John R.; Marshall, William H. 1962. Minnesota prairie management techniques and their wildlife implications. Proceedings, 27th North American Wildlife Conference. 27: 267-287. [14960]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]

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Immediate Effect of Fire

Pussy willow is normally top-killed by fire but survives by sprouting [32,87,93].
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 87. Tester, John R.; Marshall, William H. 1962. Minnesota prairie management techniques and their wildlife implications. Proceedings, 27th North American Wildlife Conference. 27: 267-287. [14960]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]

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Post-fire Regeneration

More info for the terms: adventitious, shrub

POSTFIRE REGENERATION STRATEGY [83]:
Tall shrub, adventitious buds and/or a sprouting root crown
  • 83. Stickney, Peter F. 1989. Seral origin of species comprising secondary plant succession in Northern Rocky Mountain forests. FEIS workshop: Postfire regeneration. Unpublished draft on file at: U.S. Department of Agriculture, Forest Service, Intermountain Research Station, Fire Sciences Laboratory, Missoula, MT. 10 p. [20090]

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Fire Ecology

More info for the terms: fire regime, fire-return interval, low-severity fire, natural, succession, top-kill

Fire adaptations: Pussy willow survives top-kill by fire through basal sprouting [93]. Repeated prairie fires encourage prolific sprouting [32]. Seedling establishment on burned sites was not discussed in the available literature, but given a seed source and appropriate germination conditions, is possible.

FIRE REGIMES: Sun and moist site conditions are necessary components of pussy willow habitats. Pussy willow requires canopy-opening disturbances such as flooding, ice scouring, fire, or logging to persist in most habitats. In the absence of canopy-opening disturbances, pussy willow is replaced by quaking aspen, poplar, spruce (Picea spp.), fir, or pine (Pinus spp.) woodlands or forests. In a Wisconsin brush savannah, pussy willow was more frequent on sites burned 11 times in 15 years than on adjacent unburned sites [5]. Likely pussy willow would persist indefinitely in habitats with a fire-return interval that maintained open forest or woodland canopies. Habitats with long fire-return intervals that allow forest and woodland succession to proceed would likely provide only temporary pussy willow habitat.

The following table provides fire regime information that may be relevant to pussy willow:

Fire regime information on vegetation communities in which pussy willow may occur. For each community, fire regime characteristics are taken from the LANDFIRE Rapid Assessment Vegetation Models [52]. These vegetation models were developed by local experts using available literature, local data, and/or expert opinion as documented in the PDF file linked from the name of each Potential Natural Vegetation Group listed below. Cells are blank where information is not available in the Rapid Assessment Vegetation Model.
Northern Rockies Northern Great Plains Great Lakes Northeast Southern Appalachians
Northern Rockies
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Northern Rockies Shrubland
Riparian (Wyoming)
Mixed 100% 100 25 500
Northern Rockies Forested
Ponderosa pine-Douglas-fir Replacement 10% 250   >1,000
Mixed 51% 50 50 130
Surface or low 39% 65 15  
Lower subalpine lodgepole pine Replacement 73% 170 50 200
Mixed 27% 450 40 500
Lower subalpine (Wyoming and Central Rockies) Replacement 100% 175 30 300
Northern Great Plains
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Northern Plains Grassland
Northern mixed-grass prairie Replacement 67% 15 8 25
Mixed 33% 30 15 35
Central tallgrass prairie Replacement 75% 5 3 5
Mixed 11% 34 1 100
Surface or low 13% 28 1 50
Northern tallgrass prairie Replacement 90% 6.5 1 25
Mixed 9% 63    
Surface or low 2% 303    
Southern tallgrass prairie (East) Replacement 96% 4 1 10
Mixed 1% 277    
Surface or low 3% 135    
Oak savanna Replacement 7% 44    
Mixed 17% 18    
Surface or low 76% 4    
Northern Plains Woodland
Northern Great Plains wooded draws and ravines Replacement 38% 45 30 100
Mixed 18% 94    
Surface or low 43% 40 10  
Great Plains floodplain Replacement 100% 500    
Great Lakes
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Great Lakes Woodland
Jack pine-open lands (frequent fire-return interval) Replacement 83% 26 10 100
Mixed 17% 125 10  
Great Lakes Forested
Conifer lowland (embedded in fire-prone system) Replacement 45% 120 90 220
Mixed 55% 100    
Conifer lowland (embedded in fire-resistant ecosystem) Replacement 36% 540 220 >1,000
Mixed 64% 300    
Great Lakes floodplain forest
Mixed 7% 833    
Surface or low 93% 61    
Great Lakes pine forest, jack pine Replacement 67% 50    
Mixed 23% 143    
Surface or low 10% 333
Maple-basswood-oak-aspen Replacement 4% 769    
Mixed 7% 476    
Surface or low 89% 35    
Red pine-white pine (frequent fire) Replacement 38% 56    
Mixed 36% 60    
Surface or low 26% 84    
Great Lakes pine forest, eastern white pine-eastern hemlock (frequent fire) Replacement 52% 260    
Mixed 12% >1,000    
Surface or low 35% 385    
Northeast
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Northeast Woodland
Eastern woodland mosaic Replacement 2% 200 100 300
Mixed 9% 40 20 60
Surface or low 89% 4 1 7
Northeast Forested
Eastern white pine-northern hardwoods Replacement 72% 475    
Surface or low 28% >1,000    
Northern hardwoods-spruce Replacement 100% >1,000 400 >1,000
Northeast spruce-fir forest Replacement 100% 265 150 300
Southern Appalachians
Vegetation Community (Potential Natural Vegetation Group) Fire severity* Fire regime characteristics
Percent of fires Mean interval
(years)
Minimum interval
(years)
Maximum interval
(years)
Southern Appalachians Grassland
Bluestem-oak barrens Replacement 46% 15    
Mixed 10% 69    
Surface or low 44% 16    
Eastern prairie-woodland mosaic Replacement 50% 10    
Mixed 1% 900    
Surface or low 50% 10    
*Fire Severities:
Replacement=Any fire that causes greater than 75% top removal of a vegetation-fuel type, resulting in general replacement of existing vegetation; may or may not cause a lethal effect on the plants.
Mixed=Any fire burning more than 5% of an area that does not qualify as a replacement, surface, or low-severity fire; includes mosaic and other fires that are intermediate in effects.
Surface or low=Any fire that causes less than 25% upper layer replacement and/or removal in a vegetation-fuel class but burns 5% or more of the area[40,51].
  • 5. Beck, Alan M.; Vogl, Richard J. 1972. The effects of spring burning on rodent populations in a brush prairie savanna. Journal of Mammalogy. 53(2): 336-346. [196]
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 52. LANDFIRE Rapid Assessment. 2007. Rapid assessment reference condition models. In: LANDFIRE. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Lab; U.S. Geological Survey; The Nature Conservancy (Producers). Available: http://www.landfire.gov/models_EW.php [66533]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]
  • 51. LANDFIRE Rapid Assessment. 2005. Reference condition modeling manual (Version 2.1), [Online]. In: LANDFIRE. Cooperative Agreement 04-CA-11132543-189. Boulder, CO: The Nature Conservancy; U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior (Producers). 72 p. Available: http://www.landfire.gov/downloadfile.php?file=RA_Modeling_Manual_v2_1.pdf [2007, May 24]. [66741]
  • 40. Hann, Wendel; Havlina, Doug; Shlisky, Ayn; [and others]. 2005. Interagency fire regime condition class guidebook. Version 1.2, [Online]. In: Interagency fire regime condition class website. U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; The Nature Conservancy; Systems for Environmental Management (Producer). Variously paginated [+ appendices]. Available: http://www.frcc.gov/docs/1.2.2.2/Complete_Guidebook_V1.2.pdf [2007, May 23]. [66734]

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Successional Status

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More info for the terms: bog, climax, cover, hardwood, litter, series, shrubs, succession, swamp, tree

Pussy willow is shade intolerant [50,74] and restricted to seral communities that dominate after the colonization of open water by emergent vegetation [9,18] or sites where disturbances have opened the forest canopy [14]. High levels of disturbance are tolerated [6,72]. In climax forests, pussy willow rarely exists beyond the water's edge of streams, lakes, and swamps in the absence of canopy-opening disturbances that may include fire, flooding, or logging.

Shade: Pussy willow is characterized as a "very" shade-intolerant, pioneer species in a review by Rawson [74]. A study of regenerating clearcut stands in New Brunswick showed that pussy willow abundance was greatest on disturbed sites with open canopies [72]. After tree death opened the canopy of a tamarack (Larix laricina) bog in Itasca State Park, Minnesota, large increases in pussy willow occurred [46]. In the understory of 30-year-old eastern white pine-red maple (Acer rubrum) woodland in northwestern Vermont, pussy willow shrubs were dying [43].

Disturbance: Disturbed sites are common pussy willow habitat, and shrubs withstand high levels of disturbance. In north-central British Columbia, pussy willow is common on disturbed sites [71]. After an ice storm in Missouri and Illinois, pussy willow shrubs showed little injury [17]. On the northern shore of the upper St Lawrence estuary of southern Quebec, pussy willow occurs on floodplains subject to ice flow scouring and high levels of deposition. In this highly disturbed area, the age of the oldest pussy willow was 20 years [6]. In shrub-carrs of southeastern Wisconsin, pussy willow was more common on lightly and very lightly disturbed than on moderately and severely disturbed sites. However, soil properties differed with degree of disturbance and may have affected abundance differences more than disturbance level. Severely disturbed sites were relatively dry and lightly disturbed sites were relatively wet. The water retaining capacity of lightly disturbed sites was about 20% higher than that of severely and moderately disturbed sites [93].

Primary succession: Pussy willow typically colonizes open waters after soils are deposited and/or water levels are lowered from the death and accumulation of emergent vegetation. Several studies summarize this successional process. In western Canada, sloughs are first colonized by emergent vegetation. Vegetative material accumulates as pondweed (Potamogeton spp.) grows and dies, and water levels become more shallow. Pussy willow and other willows colonize the slough following the establishment of emergent vegetation. Pussy willow is "quickly" replaced by quaking aspen unless there are periods of excessive moisture. Rates of colonization and replacement were not provided [9]. Willow-bluejoint reedgrass vegetation represents the last low-moor series in the hydrarch succession of lakes and sloughs in central Alberta. Cottonwoods (Populus spp.) dominate the next successional stage [61].

Pussy willow is common in southern shrub-carr communities in Wisconsin that represent an intermediate stage in primary hydrosere succession of lakes and ponds. These communities follow the sedge meadow stage and, in the absence of disturbances such as fire, are eventually replaced by wetland hardwood forests. Shrub-carrs can persist for 50 years or more, and tree invasion is often slow [18]. White [93] indicates that pussy willow is typically one of the last shrubs to appear in the shrub-dominated community in hydrarch primary succession in southeastern Wisconsin. In northern Minnesota, similar colonization and succession processes in open water are described by Ewing [32] and Stallard [79].

Secondary succession: Disturbance tolerance and shade intolerance make pussy willow a common early- to mid-seral species along floodplains, moist prairie sites, and logged and burned forests.

Floodplain: After dredging operations, mud was deposited on the sand flats along eastern New York's Hudson River. In 1935 sand flats were very sparsely vegetated, with an uneven scatter of eastern cottonwood (P. deltoides) and low herbaceous cover. Ten years later pussy willow occurred on the sand flats [57]. Pussy willow also occurred on alluvial fan and delta sites exposed after the draining of 2 northern Minnesota lakes. Newly created habitats were visited 9 to 15 years after their exposure. Pussy willow was among the sparse vegetation on drained portions of Bass Lake. Fourteen to 15-year-old pussy willow shrubs occurred on the drained south end of Sunken Lake in west-central Itasca County [66].

Prairie: Pussy willow populations at the edges of swamps may increase in size and spread into adjacent prairies, but without disturbances such as fire, pussy willow will be replaced by taller tree species such as quaking aspen. Initially quaking aspen establishment is slow, and if fire occurs when quaking aspen trees are very young, pussy willow will remain among the dominant woody vegetation. Visits to brush prairie vegetation in northwestern Minnesota revealed numerous clumps of pussy willow that were up to 47 years old in postfire aspen-dominated stands. Pussy willow was sparse in drier, older (6-45 years old) aspen stands but abundant in the same stands in the wettest areas: it is likely that pussy willow survived and sprouted best on the wettest burned sites [32].

Forest: Recently disturbed forests provide important pussy willow habitat. Pussy willow appears soon after the herbaceous stage of secondary succession on wet soils in climax eastern white pine forests in northern Minnesota. Pussy willow importance decreases as conifer species such as balsam fir (Abies balsamifera), northern white-cedar (Thuja occidentalis), and black spruce (Picea mariana) become established. Pussy willow is not typically present once the forest canopy closes [79]. In Itasca County, pussy willow was characteristic of shrub-dominated communities that follow the postfire herbaceous-dominated stage in pine, hardwood, and swamp forests [37]. In British Columbia's Inga Lake area, pussy willows from 10 to 20 feet (4-6 m) tall occurred in quaking aspen/cream pea (Lathyrus ochroleucus) and quaking aspen/twinberry honeysuckle (Lonicera involucrata) communities that dominated sites burned 36 years earlier [39].

Pussy willow was present only in logged black spruce stands in northeastern Ontario lowlands when logged and unlogged stands were compared. Stands were cut up to 56 years earlier. Pussy willow cover was greatest (3%) in speckled alder/deciduous leaf litter communities that dominated sites logged an average of 9.3 years before. Pussy willow cover averaged 1.3% on speckled alder/fir (Abies spp.)-black spruce/herb rich vegetation on sites logged an average of 35.5 years earlier. In stands logged an average of 1.6 years earlier, pussy willow cover was 0.4%. In black spruce/bog Labrador tea (Ledum groenlandicum)/sphagnum vegetation that dominated 28.8-year-old stands, pussy willow cover was 0.2%. Ordination of the sites revealed that speckled alder/deciduous leaf litter and speckled alder/fir-black spruce/herb rich communities were most environmentally similar, suggesting that pussy willow cover differences were better attributed to site differences than time since logging [14].

  • 6. Begin, Yves. 1990. The effects of shoreline transgression on woody plants, upper St. Lawrence estuary, Quebec. Journal of Coastal Research. 6(4): 815-827. [17681]
  • 9. Bird, Ralph D. 1961. Ecology of the aspen parkland of western Canada in relation to land use. Contribution No. 27. Ottawa: Canada Department of Agriculture, Research Branch. 153 p. [15620]
  • 14. Brumelis, G.; Carleton, T. J. 1989. The vegetation of post-logged black spruce lowlands in central Canada. II. Understory vegetation. Journal of Applied Ecology. 26: 321-339. [7864]
  • 17. Croxton, W. C. 1939. A study of the tolerance of trees to breakage by ice accumulation. Ecology. 20: 71-73. [5993]
  • 18. Curtis, John T. 1959. Tall shrub communities. In: Curtis, John T. The vegetation of Wisconsin. Madison, WI: The University of Wisconsin Press: 352-358. [60529]
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 37. Grant, Martin L. 1929. The burn succession in Itasca County, Minnesota. Minneapolis, MN: University of Minnesota. 63 p. Thesis. [36527]
  • 39. Haeussler, Sybille; Bedford, Lorne; Boateng, Jacob O.; MacKinnon, Andy. 1999. Plant community responses to mechanical site preparation in northern interior British Columbia. Canadian Journal of Forest Research. 29: 1084-1100. [38978]
  • 43. Howard, Lauren Davis. 1983. A simple system for relating physiognomy, floristic composition and relative importance in woody vegetation. Bulletin of the Torrey Botanical Club. 110(3): 360-365. [67532]
  • 46. Isaak, Daniel; Marshall, William H.; Buell, Murray F. 1959. A record of reverse plant succession in a tamarack bog. Ecology. 40(2): 317-320. [10551]
  • 50. Kudish, Michael. 1992. Adirondack upland flora: an ecological perspective. Saranac, NY: The Chauncy Press. 320 p. [19376]
  • 57. McVaugh, Rogers. 1947. Establishment of vegetation on sand-flats along the Hudson River, New York. Ecology. 28(2): 189-193. [67550]
  • 61. Moss, E. H. 1932. The vegetation of Alberta: IV. The poplar association and related vegetation of central Alberta. The Journal of Ecology. 20(2): 380-415. [63588]
  • 66. Nielsen, Etlar L.; Moyle, John B. 1941. Forest invasion and succession on the basins of two catastrophically drained lakes in northern Minnesota. The American Midland Naturalist. 25(3): 564-579. [62782]
  • 71. Porter, Glen L. 1990. Willow species of disturbed sites in the sub-boreal spruce zone in north-central British Columbia. FRDA Handbook 004; ISSN-0835-1929. Victoria, BC: Forestry Canada; B.C. Ministry of Forests. 67 p. [28015]
  • 72. Ramovs, B. V.; Roberts, M. R. 2005. Response of plant functional groups within plantations and naturally regenerated forests in southern New Brunswick, Canada. Canadian Journal of Forest Research. 35(6): 1261-1276. [61144]
  • 74. Rawson, James W. 1974. Willows. In: Gill, John D.; Healy, William M. Shrubs and vines for northeastern wildlife. Gen. Tech. Rep. NE-9. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 147-149. [51835]
  • 79. Stallard, Harvey. 1929. Secondary succession in the climax forest formations of northern Minnesota. Ecology. 10(4): 476-547. [3808]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]

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Regeneration Processes

More info for the terms: bog, cover, dioecious, fresh, litter, protandrous, shrubs

Pussy willow regenerates asexually by sprouting [71,74,93] and sexually through seed production and germination [62,79].

Pollination: Pussy willow flowers are insect and wind pollinated. Bumblebees, butterflies, flies, and ants visit willow flowers for nectar and pollen. In many areas, willows provide the first and most important bee forage [19]. During pollination and hybridization experiments with pussy willow in the Central Research Forest near Ottawa, Ontario, Kevan (personal communication in [3]) observed many insects visiting pussy willow. However, shrubs isolated from insect visitors produced abundant seed, indicating that fertilization occurred without insect visitors [3].

High-sugar nectar is produced by pussy willow. Five pussy willow catkins collected from a Maine bog had about 200 nectar-bearing flowers each and averaged 2.2 μL of nectar and 1.4 mg of sugar. The amount of sugar in pussy willow catkins was the highest of the 17 associated species evaluated [41].

Breeding system: Pussy willow shrubs are dioecious [80] and protandrous [3].

Seed production: Studies on pussy willow seed production are lacking. A review reports that "optimum" seed production occurs when shrubs are 8 to 25 years old [74]. In seral communities on wet sites that eventually support eastern white pine (Pinus strobus) communities in northern Minnesota, pussy willow produced a "great abundance" of seed. Seeds were so numerous that they blanketed the soil surface [79].

Seed dispersal: Small willow seeds are easily dispersed by wind [19]. A review by Rawson [74] reports that pussy willow seeds are dispersed by both wind and water. On the reclaimed Fresh Kills Landfill on Staten Island, New York, a single pussy willow seedling emerged, and the nearest seed source was 942 feet (287 m) away [75].

Seed banking: Willow seeds are typically viable for just a few days [19]. In the only experiment on pussy willow seed found for this review (2007), a rapid decrease in germination rate occurred after freshly harvested seed was kept for 2 weeks at room temperature [62].

Germination: Studies of pussy willow seed germination are lacking. Pussy willow seed collected in Edmonton, Alberta, germinated at a 50% level when fresh [62]. Based on observations made in pussy willow habitats, Stallard [79] suggested that seeds germinated best on wet or moist soils but would not germinate in submerged soils.

Seedling establishment/growth: No research describes the factors affecting pussy willow seedling establishment. It is reported, though, that 2- to 3-year-old pussy willow seedlings survive submergence [79]. In a shrub-carr adjacent to White Clay Lake in Wisconsin, pussy willow cover was significantly greater on alluvial than histic surface soils (P<0.01). Alluvial soils received recent sediment deposition and were litter-free. The researcher suggested that the leaf litter and grasses that covered histic soils may have restricted seedling establishment [48].

Vegetative regeneration: Pussy willow regenerates vegetatively from basal sprouts [74], and broken branches that lodge in moist soil may root and grow. There are reports of willows used as fence posts that rooted and grew into shrubs or trees [19].

Aboveground stem death promotes basal sprouting. Ewing [32] describes pussy willow postfire sprouting as prolific. Stem death from borer beetles also encourages sprouting [93]. Two years after pussy willow shrubs were cut down in north-central British Columbia, sprouts were over 8.2 feet (2.5 m) tall [71].

  • 3. Argus, George W. 1974. An experimental study of hybridization and pollination in Salix (willow). Canadian Journal of Botany. 52(7): 1613-1619. [67515]
  • 19. Dalby, Richard. 1999. Willows are wonderful. American Bee Journal. 139(3): 220-221. [67517]
  • 32. Ewing, J. 1924. Plant successions of the brush-prairie in north-western Minnesota. Journal of Ecology. 12: 238-266. [11122]
  • 41. Heinrich, Bernd. 1975. Bee flowers: a hypothesis on flower variety and blooming times. Evolution. 29(2): 325-334. [67540]
  • 48. Johnston, Carol A. 2003. Shrub species as indicators of wetland sedimentation. Wetlands. 23(4): 911-920. [67520]
  • 62. Moss, E. H. 1938. Longevity of seed and establishment of seedlings in species of Populus. Botanical Gazette. 99: 529-542. [26846]
  • 71. Porter, Glen L. 1990. Willow species of disturbed sites in the sub-boreal spruce zone in north-central British Columbia. FRDA Handbook 004; ISSN-0835-1929. Victoria, BC: Forestry Canada; B.C. Ministry of Forests. 67 p. [28015]
  • 74. Rawson, James W. 1974. Willows. In: Gill, John D.; Healy, William M. Shrubs and vines for northeastern wildlife. Gen. Tech. Rep. NE-9. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 147-149. [51835]
  • 75. Robinson, George R.; Handel, Steven N. 1993. Forest restoration on a closed landfill: rapid addition of new species by bird dispersal. Conservation Biology. 7(2): 271-278. [22062]
  • 79. Stallard, Harvey. 1929. Secondary succession in the climax forest formations of northern Minnesota. Ecology. 10(4): 476-547. [3808]
  • 80. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]

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Growth Form (according to Raunkiær Life-form classification)

More info on this topic.

More info for the term: phanerophyte

RAUNKIAER [73] LIFE FORM:
Phanerophyte
  • 73. Raunkiaer, C. 1934. The life forms of plants and statistical plant geography. Oxford: Clarendon Press. 632 p. [2843]

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Life Form

More info for the terms: shrub, tree

Shrub-tree

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Ecology

The plant can resprout after physical damage. (USDA PLANTS, 2009)
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Life History and Behavior

Cyclicity

Phenology

More info on this topic.

More info for the terms: natural, phenology

Pussy willow flowers in early spring (March-May), and flowers appear before the leaves. Fruits ripen soon after flowering [42,74].

Reproductive phenology of pussy willow by state, province, or region
State/province/region Reproductive phenology (flowering/fruiting/seed dispersal)
Adirondacks fruits ripen in late spring [16]
Atlantic coast from New York to Newfoundland catkins emerge in April [28]
Great Plains (north) flowers mid-April-early May; fruits mid-May-early June [53]
Illinois catkins March-May [60]
Illinois (Morton Arboretum's East Woods) early flower date was 30 March and late flower date was 8 May after 15 years of observations [95]
Plains (north-central) flowers in May; fruits in June [80]
New York (Fire Island, Suffolk County) flowers in April [27]
North Dakota (Fargo) average flowering date from 3 or more years was 23 April [82]
Northeast flowers in March-April [74]
West Virginia flowers in March-May [84]
British Columbia (north-central) seed dispersal begins in May [71]

Flowering was observed in pussy willow grown from natural cuttings in a common garden with other willows near Maple, Ontario. The pussy willow flowering period was short, and averages ranged from 6.4 to 12.7 days over the 3 years of study. Early-flowering willows were reproductively isolated from late-flowering species in all but 1 of 3 years, suggesting that annual weather patterns may affect hybridization potential. Over the 3-year study, researchers recorded the appearance of male and female flowers at the same time, female flowers first, and male flowers first. The earliest flower receptivity date was 6 April, and the latest receptivity date was 2 May. Flower buds were produced the season before flowering, and researchers presumed that flower development was controlled by "temperature thresholds" or "accumulated heat units" [65].

  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
  • 16. Chapman, William K.; Bessette, Alan E. 1990. Trees and shrubs of the Adirondacks. Utica, NY: North Country Books, Inc. 131 p. [12766]
  • 27. Dowhan, Joseph J.; Rozsa, Ron. 1989. Flora of Fire Island, Suffolk County, New York. Bulletin of the Torrey Botanical Club. 116(3): 265-282. [22041]
  • 28. Duncan, Wilbur H.; Duncan, Marion B. 1987. The Smithsonian guide to seaside plants of the Gulf and Atlantic coasts from Louisiana to Massachusetts, exclusive of lower peninsular Florida. Washington, DC: Smithsonian Institution Press. 409 p. [12906]
  • 42. Hewsholme, Christopher. 1992. Willows: The genus Salix. Portland, OR: Timber Press, Inc. 224 p. [20106]
  • 65. Mosseler, A.; Papadopol, C. S. 1989. Seasonal isolation as a reproductive barrier among sympatric Salix species. Canadian Journal of Botany. 67: 2563-2570. [10066]
  • 71. Porter, Glen L. 1990. Willow species of disturbed sites in the sub-boreal spruce zone in north-central British Columbia. FRDA Handbook 004; ISSN-0835-1929. Victoria, BC: Forestry Canada; B.C. Ministry of Forests. 67 p. [28015]
  • 74. Rawson, James W. 1974. Willows. In: Gill, John D.; Healy, William M. Shrubs and vines for northeastern wildlife. Gen. Tech. Rep. NE-9. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 147-149. [51835]
  • 80. Stephens, H. A. 1973. Woody plants of the North Central Plains. Lawrence, KS: The University Press of Kansas. 530 p. [3804]
  • 82. Stevens, O. A. 1921. Plants of Fargo, North Dakota, with dates of flowering. I. The American Midland Naturalist. 7(2): 54-62. [49786]
  • 95. Wilhelm, Gerould S. 1991. Implications of changes in floristic composition of the Morton Arboretum's East Woods. In: Burger, George V.; Ebinger, John E.; Wilhelm, Gerould S., eds. Proceedings of the oak woods management workshop; 1988 October 21-22; Peoria, IL. Charleston, IL: Eastern Illinois University: 31-54. [49325]
  • 60. Mohlenbrock, Robert H. 1986. [Revised edition]. Guide to the vascular flora of Illinois. Carbondale, IL: Southern Illinois University Press. 507 p. [17383]
  • 53. Larson, Gary E. 1993. Aquatic and wetland vascular plants of the Northern Great Plains. Gen. Tech. Rep. RM-238. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 681 p. Jamestown, ND: Northern Prairie Wildlife Research Center (Producer). Available: http://www.npwrc.usgs.gov/resource/plants/vascplnt/vascplnt.htm [2006, February 11]. [22534]

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This plant flowers in April and sprouts leaves in May. (Peattie, 1930) The familiar, silvery-gray, furry catkins appear before leaf emergence. This plant is deciduous. The large flower buds burst and expose their soft silky hair, or pussy fur, early in the year. Pussy willow catkins are the first willow catkins to appear each year and are recognized as a sign of spring. Bloom time is February to March. (NPIN, 2007) Active growth period is the Spring. Fruit/seed period begins and ends in the Spring. (USDA PLANTS, 2009)
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Life Expectancy

Short-lived and fast-growing. (NPIN, 2007)
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Molecular Biology and Genetics

Molecular Biology

Statistics of barcoding coverage: Salix discolor

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 15
Specimens with Barcodes: 32
Species With Barcodes: 1
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Source: Barcode of Life Data Systems (BOLD)

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Conservation

Conservation Status

National NatureServe Conservation Status

Canada

Rounded National Status Rank: NNR - Unranked

United States

Rounded National Status Rank: N5 - Secure

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NatureServe Conservation Status

Rounded Global Status Rank: G5 - Secure

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Information on state-level protected status of plants in the United States is available at Plants Database.

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This plant is listed by the U.S. federal government or a state. Common names are from state and federal lists. In Kentucky the pussy willow is listed as Historical. (USDA PLANTS, 2009)
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Management

Management considerations

More info for the terms: shrub, shrubs

Herbicide effects: Articles written
between 1948 and 1950 provide information on the effects of herbicide on pussy
willow shrubs in Connecticut [29,30,31].



Pests: Borers and beetles attack pussy
willow. Pussy willow deaths from willow borers (Sternochetus
lapathi) are occasional in the Black Hills of South Dakota [34]. In
southeastern Wisconsin, the many tunnels made by borer beetle larvae weaken and kill
pussy willow stems. Sprouting is common after stem death [93].
In western Canada, pussy willow is considered the "favorite food plant"
of Galerucella decora beetles. Beetles will completely defoliate pussy willow
before moving on to other willow species [9].
Estimating shrub dimensions and biomass:
In northeastern Minnesota, equations were developed to estimate leaf, stem, current
year's stem, and total biomass for willows from plant height, crown area, or stem
diameter. Equations were developed from data collected in regenerating clearcuts,
but the willow species were not identified [67]. Additional
regression equations were developed from data collected in northeastern
Minnesota to determine canopy area and volume from a variety of pussy willow measurements.
Data used in equation development came from shrubs growing on well-drained
soils, with a sparse to nonexistent overstory [70].

  • 9. Bird, Ralph D. 1961. Ecology of the aspen parkland of western Canada in relation to land use. Contribution No. 27. Ottawa: Canada Department of Agriculture, Research Branch. 153 p. [15620]
  • 34. Froiland, Sven G. 1962. The genus Salix (willows) in the Black Hills of South Dakota. Technical Bulletin No. 1269. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment Station. 75 p. [5992]
  • 93. White, Keith L. 1965. Shrub-carrs of southeastern Wisconsin. Ecology. 46(3): 286-304. [8858]
  • 29. Egler, Frank E. 1948. 2,4-D effects in Connecticut vegetation, 1947. Ecology. 29(3): 382-386. [60983]
  • 30. Egler, Frank E. 1949. Herbicide effects in Connecticut vegetation, 1948. Ecology. 30(2): 248-256. [60965]
  • 31. Egler, Frank E. 1950. Herbicide effects in Connecticut vegetation, 1949. Botanical Gazette. 112(1): 76-85. [61003]
  • 67. Ohmann, Lewis F.; Grigal, David F.; Brander, Robert B. 1976. Biomass estimation for five shrubs from northeastern Minnesota. Res. Pap. NC-133. St. Paul, MN: U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station. 11 p. [20786]
  • 70. Peek, James M. 1970. Relation of canopy area and volume to production of three woody species. Ecology. 51(6): 1098-1101. [64408]

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Relevance to Humans and Ecosystems

Benefits

Cultivation

The preference is full sun, wet to moist conditions, and sandy or non-sandy soil with some decaying organic matter. The easiest method of propagation is to cut off a branch and stick it into moist ground. The branch will eventually form leaves at the top and develop roots underground. It also possible to scatter the tiny seeds across the ground, but it will take longer to develop a mature shrub. Because the seeds remain viable for only a week or two, they must be sown immediately.
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Importance to Livestock and Wildlife

More info for the terms: cover, frequency, marsh

In a review, Rawson [74] reports that deer, moose, rabbits, and rodents browse pussy willow stems and that ducks and other water fowl feed on pussy willow catkins. Other studies indicate that pussy willow is also forage for cattle [58], caribou [7], muskrats [85], ruffed grouse [12], and Galerucella decora beetles [9]. Of these wildlife species, pussy willow is most important to moose and Galerucella decora beetles.

Livestock: Cattle browsed pussy willow in sedge (Carex spp.) meadows in southern Wisconsin's Lodi Marsh [58].

Native ungulates: Caribou browsed pussy willow in the summer and winter in Newfoundland [7], moose utilized pussy willow year-round in Minnesota [69], and white-tailed deer browsed pussy willow on winter ranges in Minnesota and Quebec [13,44].

Caribou: Rumina of Newfoundland caribou had a low frequency of pussy willow in the summer (7%) and in the winter (3%) [7].

Moose: A review reports that willows are browsed by moose throughout their range, and that pussy willow provides important moose winter forage in western Montana [68]. Willows (pussy willow, Bebb willow, and sandbar willow) made up 25% of the total moose diet from April to December on 2-year-old burned boreal forest sites northwest of Ely, Minnesota [45]. In northeastern Minnesota, upland willows (pussy willow, Bebb willow, and prairie willow) were utilized year round by moose. Use averaged 26% for the year and was slightly greater from October to December than from January to April and from June to September. When availability of the vegetation was evaluated with moose use, researchers suggested that upland willows were the most palatable. Pussy willow was consumed more than the other willow species when species were identifiable [69].

Deer: Pussy willow is not often the most palatable forage available to white-tailed deer but is an important winter food. In browse surveys conducted on the Apostle Islands of Lake Superior in northern Wisconsin, researchers grouped pussy willow in the 3rd choice browse group out of 4 possible groups [4]. In the Mud Lake National Wildlife Refuge of Marshall County, Minnesota, willows provided the bulk of the winter food consumed by white-tailed deer (about 45%), although willows were not the most palatable food available. Pussy willow was 1 of 10 willows present in the study area [44]. In the Rigaud white-tailed deer wintering area in southwestern Quebec, pussy willow use increased as winter progressed and with each progressive sampling year. In the 1st sampling winter, 13.5% of available pussy willow stems were browsed, and by the 3rd winter 21.4% of available stems were browsed [13].

Small mammals: Pussy willow occurred in muskrat "feeding platforms" (areas where muskrats bring food to consume) in the Corinna marsh area of central Maine, although pussy willow was not encountered in any quadrat during a vegetation survey of the study area [85].

Birds: Pussy willow was the 2nd most important winter food for ruffed grouse collected throughout Maine. Pussy willow buds and leaves made up 8.8% of the contents of digestive tracts taken in the winter and 3.6% of tracts collected in the spring. The researcher indicated that these percentages may include other willow species but that pussy willow was most common [12].

Insects: In western Canada, Galerucella decora beetles will defoliate pussy willow, their "favorite food plant", before moving on to other willow species [9].

Palatability/nutritional value: The nutritional content of pussy willow is reported for the terminal 3 inches of current year's stems collected in December in northeastern Minnesota: N=1.1%, P=0.2% K=0.7%, Ca=1.3%, and crude protein=8.2% [69]. Available palatability information was integrated into the above Importance to Livestock and Wildlife section.

Cover value: In a review, Rawson [74] reports that pussy willow thickets provide bird and mammal cover.

  • 9. Bird, Ralph D. 1961. Ecology of the aspen parkland of western Canada in relation to land use. Contribution No. 27. Ottawa: Canada Department of Agriculture, Research Branch. 153 p. [15620]
  • 45. Irwin, Larry L. 1985. Foods of moose, Alces alces, and white-tailed deer, Odocoileus virginianus, on a burn in boreal forest. The Canadian Field-Naturalist. 99(2): 240-245. [4513]
  • 74. Rawson, James W. 1974. Willows. In: Gill, John D.; Healy, William M. Shrubs and vines for northeastern wildlife. Gen. Tech. Rep. NE-9. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station: 147-149. [51835]
  • 4. Beals, E. W.; Cottam, G.; Vogl, R. J. 1960. Influence of deer on vegetation of the Apostle Islands, Wisconsin. Journal of Wildlife Management. 24(1): 68-80. [67570]
  • 7. Bergerud, Arthur T. 1972. Food habits of Newfoundland caribou. Journal of Wildlife Management. 36(3): 913-923. [14760]
  • 12. Brown, Charles P. 1946. Food of Maine ruffed grouse by seasons and cover types. Journal of Wildlife Management. 10(1): 17-28. [67563]
  • 13. Brown, David T.; Doucet, G. Jean. 1991. Temporal changes in winter diet selection by white-tailed deer in a northern deer yard. Journal of Wildlife Management. 55(3): 361-376. [15406]
  • 44. Hunt, Robley W.; Mangus, Lloyd M. 1954. Deer management study: Mud Lake National Wildlife Refuge, Holt, Minnesota. Journal of Wildlife Management. 18(4): 482-495. [67535]
  • 58. Middleton, Beth. 2002. Nonequilibrium dynamics of sedge meadows grazed by cattle in southern Wisconsin. Plant Ecology. 161: 89-110. [6628]
  • 68. Peek, J. M. 1974. A review of moose food habits studies in North America. Le Naturaliste Canadien. 101: 195-215. [7420]
  • 69. Peek, James M., Urich, David L.; Mackie, Richard J. 1976. Moose habitat selection and relationships to forest management in northeastern Minnesota. Wildlife Monographs No. 48. Washington, DC: The Wildlife Society. 65 p. [13902]
  • 85. Takos, Michael J. 1947. A semi-quantitative study of muskrat food habits. Journal of Wildlife Management. 11(4): 331-339. [67566]

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Value for rehabilitation of disturbed sites

Pussy willow and other willow species grow rapidly and produce extensive root systems that bind soil and decrease erosion [19], making them an obvious choice for site-appropriate revegetation and rehabilitation programs.

Researchers have used pussy willow in vegetative filter strip plantings between agricultural areas and waterways or wetlands to improve water quality, through the removal of nutrients and sediments produced by agriculture operations. Pussy willow stems can be harvested as early as 2 years after establishment. Selling pussy willow stems to florists soon after the establishment of filter strips can augment the cost of their construction. Rapid sprouting provides for a short-term and continued economic return [59].

  • 19. Dalby, Richard. 1999. Willows are wonderful. American Bee Journal. 139(3): 220-221. [67517]
  • 59. Miller, B. K.; Moser, B. C.; Johnson, K. D.; Swihart, R. K. 1994. Designs for windbreaks and vegetative filterstrips that increase wildlife habitat and provide income. In: Campbell, Kenneth L.; Graham, Wendy D.; Bottcher, A. B., eds. Environmentally sound agriculture: Proceedings of the 2nd conference; 1994 April 20-22; Orlando, FL. St. Joseph, MI: American Society of Agricultural Engineers: 567-574. [67523]

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Other uses and values

Today pussy willow twigs with immature catkins are used in floral arrangements [33]. In the past, willow bark, which contains salicin (a close relative of acetylsalicylic acid) was used to treat variety of ailments such as fevers, pains, colds, and rheumatism [19].
  • 19. Dalby, Richard. 1999. Willows are wonderful. American Bee Journal. 139(3): 220-221. [67517]
  • 33. Farrar, John Laird. 1995. Trees of the northern United States and Canada. Ames, IA: Blackwell Publishing. 502 p. [60614]

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Uses

In winter, cut Pussy Willow twigs can be put in water and the flowers forced at warm temperatures. (NPIN, 2007)

Native American uses include: Various treatments of branches are used to start lactation, as a painkiller, for fevers, for bleeding hemorrhoids, for stomach troubles, for trembling, for fainting, as a universal remedy, for "sick" throats, and for diarrhea. Compound decoction taken to vomit to reduce loneliness. Spring buds used to make a red dye. Bark and stems used to make various containers, ties, and tools. (UM, 2009)

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Wikipedia

Salix discolor

Salix discolor (American willow[1]) is a species of willow native to North America, one of two species commonly called pussy willow.

It is native to the northern forests and wetlands of Canada (British Columbia east to Newfoundland), and is also found in the northern portions of the contiguous United States (Idaho east to Maine, and south to Maryland).[1][2][3]

It is a weak-wooded deciduous shrub or small tree growing to 6 m (20 ft) tall, with brown shoots. The leaves are oval, 3–14 cm long and 1-3.5 cm broad, green above and downy grey-white beneath.

The flowers are soft silky silvery catkins, borne in early spring before the new leaves appear, with the male and female catkins on different plants (dioecious); the male catkins mature yellow at pollen release.

The fruit is a small capsule 7–12 mm long containing numerous minute seeds embedded in cottony down.[2][3]

Cultivation and uses[edit]

Like other willows, it contains salicin, and was used by Native Americans as a painkiller.[3]

As with the closely related Salix caprea (European pussy willow), it is also often grown for cut flowers. Pussy willow has further cultural information and other uses.

References[edit]

  1. ^ a b Germplasm Resources Information Network: Salix discolor
  2. ^ a b Plants of British Columbia: Salix discolor
  3. ^ a b c Borealforests: Salix discolor
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Names and Taxonomy

Taxonomy

More info for the term: natural

The scientific name of pussy willow is Salix discolor Muhl. (Salicaceae) [36,38,49,92].
Pussy willow belongs to the Caprisalix subgenus and the Vetrix section of the Salicaceae family
[42].

Infrataxa: The following varieties are recognized by
some systematists:

   Salix discolor var. latifolia [11,27,60,84,92,94]

   Salix discolor var. discolor [11,92,94]
Hybrids: Voss [92] considers pussy willow
hybridization common, but others have identified many potential barriers to natural
hybridization [63,64,65].
Hybrids with Bebb willow (S. bebbiana) are reported [35,50], and some
suggest that hybrids with prairie willow (S. humilis) [36] and Scouler
willow (S. scouleriana) are possible [71].
  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
  • 36. Gleason, Henry A.; Cronquist, Arthur. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. 2nd ed. New York: New York Botanical Garden. 910 p. [20329]
  • 92. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472]
  • 11. Braun, E. Lucy. 1961. The woody plants of Ohio. Columbus, OH: Ohio State University Press. 362 p. [12914]
  • 27. Dowhan, Joseph J.; Rozsa, Ron. 1989. Flora of Fire Island, Suffolk County, New York. Bulletin of the Torrey Botanical Club. 116(3): 265-282. [22041]
  • 38. Great Plains Flora Association. 1986. Flora of the Great Plains. Lawrence, KS: University Press of Kansas. 1392 p. [1603]
  • 42. Hewsholme, Christopher. 1992. Willows: The genus Salix. Portland, OR: Timber Press, Inc. 224 p. [20106]
  • 50. Kudish, Michael. 1992. Adirondack upland flora: an ecological perspective. Saranac, NY: The Chauncy Press. 320 p. [19376]
  • 63. Mosseler, A. 1989. Interspecific pollen-pistil incongruity in Salix. Canadian Journal of Forest Research. 19: 1161-1168. [9348]
  • 64. Mosseler, A. 1990. Hybrid performance and species crossability relationships in willows. Canadian Journal of Botany. 68(11): 2329-2338. [60064]
  • 65. Mosseler, A.; Papadopol, C. S. 1989. Seasonal isolation as a reproductive barrier among sympatric Salix species. Canadian Journal of Botany. 67: 2563-2570. [10066]
  • 71. Porter, Glen L. 1990. Willow species of disturbed sites in the sub-boreal spruce zone in north-central British Columbia. FRDA Handbook 004; ISSN-0835-1929. Victoria, BC: Forestry Canada; B.C. Ministry of Forests. 67 p. [28015]
  • 35. Gates, Frank C. 1930. Aspen association in northern lower Michigan. Botanical Gazette. 40(3): 233-259. [16933]
  • 94. White, W. W. 1956. Native willows found in Montana. Proceedings of the Montana Academy of Science. 16: 21-35. [6001]
  • 49. Kartesz, John T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. 1st ed. In: Kartesz, John T.; Meacham, Christopher A. Synthesis of the North American flora (Windows Version 1.0), [CD-ROM]. Chapel Hill, NC: North Carolina Botanical Garden (Producer). In cooperation with: The Nature Conservancy; U.S. Department of Agriculture, Natural Resources Conservation Service; U.S. Department of the Interior, Fish and Wildlife Service. [36715]
  • 60. Mohlenbrock, Robert H. 1986. [Revised edition]. Guide to the vascular flora of Illinois. Carbondale, IL: Southern Illinois University Press. 507 p. [17383]

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Synonyms

Salix discolor var. overi Ball [92]=

   Salix discolor [49]


Salix discolor var. prinoides (Pursh) Anderss. [84,94]=

   Salix discolor [49]
  • 84. Strausbaugh, P. D.; Core, Earl L. 1977. Flora of West Virginia. 2nd ed. Morgantown, WV: Seneca Books, Inc. 1079 p. [23213]
  • 92. Voss, Edward G. 1985. Michigan flora. Part II. Dicots (Saururaceae--Cornaceae). Bull. 59. Bloomfield Hills, MI: Cranbrook Institute of Science; Ann Arbor, MI: University of Michigan Herbarium. 724 p. [11472]
  • 94. White, W. W. 1956. Native willows found in Montana. Proceedings of the Montana Academy of Science. 16: 21-35. [6001]
  • 49. Kartesz, John T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. 1st ed. In: Kartesz, John T.; Meacham, Christopher A. Synthesis of the North American flora (Windows Version 1.0), [CD-ROM]. Chapel Hill, NC: North Carolina Botanical Garden (Producer). In cooperation with: The Nature Conservancy; U.S. Department of Agriculture, Natural Resources Conservation Service; U.S. Department of the Interior, Fish and Wildlife Service. [36715]

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Common Names

pussy willow

American pussy willow

glaucous willow

large pussy willow

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