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National Distribution


Origin: Exotic

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

United States

Origin: Exotic

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe


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More info for the terms: cover, natural

Perennial sowthistle is of European [53,109] and western Asian [109] origin and was probably introduced into North America as a seed contaminant [75]. Sonchus arvensis spp. arvensis was first reported in 1814 in Pennsylvania [109]. The earliest collection of S. a. ssp. glabrescens in North America was from Maine in 1894. Additional collections were reported from Massachusetts and Ohio as early as 1902 [37].

Perennial sowthistle is reported throughout most of the United States, with the exception of Hawaii, Arizona, Oklahoma, Arkansas, Alabama, Georgia, South Carolina, and Florida. It occurs throughout Canada. Sonchus arvensis spp. arvensis has the same distribution as perennial sowthistle, but it is not recorded in Nebraska, Kansas, Virginia, West Virginia, North Carolina, or Alaska. Sonchus arvensis spp. uliginosus occurs across the northern portion of North America, from Alaska south to Oregon and Utah, and east to Virginia and North Carolina; but it is not reported in New Hampshire, Kentucky, British Columbia or the far northern territories of Canada [65].

No specific mention of perennial sowthistle in Mexico occurs in the literature. Since it occurs in Texas and New Mexico, it is reasonable to assume it may also occur in northern Mexico.

Plants database provides a state distribution map of perennial sowthistle and its infrataxa.

The following lists include North American ecosystems, habitat types, and forest and range cover types in which perennial sowthistle may occur. Perennial sowthistle grows well in wet and even saturated soils. Consequently, perennial sowthistle may occur in riparian areas or wetlands within these habitats. Additionally, perennial sowthistle often occurs in cultivated areas, especially small grain and row crops, so it may occur in cultivated areas within these communities, with the potential to spread into adjacent, undisturbed areas.

These lists are not necessarily inclusive or exhaustive. More information is needed to determine particular ecosystems and plant communities where perennial sowthistle is likely to occur in natural areas.


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States or Provinces

(key to state/province abbreviations)



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Regional Distribution in the Western United States

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):


1 Northern Pacific Border

2 Cascade Mountains

3 Southern Pacific Border

4 Sierra Mountains

5 Columbia Plateau

6 Upper Basin and Range

7 Lower Basin and Range

8 Northern Rocky Mountains

9 Middle Rocky Mountains

10 Wyoming Basin

11 Southern Rocky Mountains

12 Colorado Plateau

13 Rocky Mountain Piedmont

14 Great Plains

15 Black Hills Uplift

16 Upper Missouri Basin and Broken Lands


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Physical Description



More info for the terms: achene, pappus

The following description of perennial sowthistle provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for identification are available in these sources: [26,34,42,45].

Perennial sowthistle is a perennial herb [53,74] that reproduces by seeds, by vertical, thickened roots, and by cylindrical, horizontal, spreading roots [110]. Vertical roots can penetrate 5 to10 feet (1.5-3  m) deep. Horizontal roots, frequently 2.5 to 5 mm in diameter (rarely exceeding 10 mm), are found 2 to 4 inches (5-10 cm) below the soil surface [10]. These horizontal roots can reach 3 to 6 feet (0.9-1.8 m) in length in a single growing season [110]. Fruits are achenes [15,90] with a pappus that generally stays attached to the achene [92].

Stems are erect, 0.1 to 0.4 inches (3-10 mm) in diameter, and most commonly 24 to 59 inches (60-150 cm) tall; although they range from 12 to 71 inches (30-180 cm) tall. Stems are hollow and branched, varying from 2 to many per plant. Leaves are crowded on the lower stems and sparse on the upper stems. The entire plant is filled with milky latex [74].


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Perennials, 0–150(–200) cm, usually rhizomatous or stoloni-ferous. Stem bases hard, some-times ± woody. Leaves: blades of mid cauline oblong to lanceolate, (3–)6–40 × 2–15 cm, bases auriculate, auricles straight or curved, rounded, margins usually pinnately lobed, lobes ± deltate, not constricted at bases, terminals usually larger than laterals, dentate or entire. Peduncles sessile- or stipitate-glandular. Involucres 10–17+ mm. Phyllaries sessile- or stipitate-glandular. Corollas: ligules ± equaling tubes. Cypselae dark brown, oblanceoloid to ellipsoid, 2.5–3.5 mm, ribs 4–5(+) on each face, faces transversely rugulose to tuberculate across and between ribs; pappi 8–14 mm. 2n = 36, 54.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA

Source: Missouri Botanical Garden


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Habitat characteristics

Perennial sowthistle is adapted to moist, sunny locations in temperate regions but is absent from tropical areas [74]. Within temperate regions, perennial sowthistle has a broad tolerance to variable environments and adapts well to wet sites, even with little soil disturbance. In Canada, perennial sowthistle occurs in areas that receive average annual precipitation of 12 to 120 inches (300-3,000 mm) [133]. In a greenhouse study, growth of perennial sowthistle plants was positively correlated with increasing soil water, with greatest growth occurring at complete saturation [132]. However, perennial sowthistle also establishes on dry sites [98]. Neither the climatic conditions required for successful establishment nor conditions, if any, favoring S. a. ssp. arvensis over S. a. ssp. uliginosus have been established [74].

Perennial sowthistle is adapted to many soil types but appears to prefer fine-textured soils and does not thrive on dry, coarse-textured sand. Perennial sowthistle seems to prefer slightly alkaline or neutral soils and does not thrive in acid soils, salt marshes, or highly alkaline areas [110]. However, Zollinger and Kells [132] determined soil pH had little effect on leaf production, plant height, or number of capitula produced.

Perennial sowthistle is present in a variety of community types from those occurring on wet, very strongly saline surface soil and strongly saline subsoil to nonsaline and dry soils [98]. Dodd and Coupland [33] describe perennial sowthistle as occurring in halophytic or semihalophytic communities in Saskatchewan.


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Habitat: Rangeland Cover Types

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, fresh, lichen, mesic, shrub, tussock, vine


101 Bluebunch wheatgrass

102 Idaho fescue

103 Green fescue

104 Antelope bitterbrush-bluebunch wheatgrass

105 Antelope bitterbrush-Idaho fescue

106 Bluegrass scabland

107 Western juniper/big sagebrush/bluebunch wheatgrass

108 Alpine Idaho fescue

109 Ponderosa pine shrubland

110 Ponderosa pine-grassland

201 Blue oak woodland

202 Coast live oak woodland

203 Riparian woodland

204 North coastal shrub

205 Coastal sage shrub

206 Chamise chaparral

207 Scrub oak mixed chaparral

208 Ceanothus mixed chaparral

209 Montane shrubland

210 Bitterbrush

211 Creosote bush scrub

212 Blackbush

213 Alpine grassland

214 Coastal prairie

215 Valley grassland

216 Montane meadows

217 Wetlands

301 Bluebunch wheatgrass-blue grama

302 Bluebunch wheatgrass-Sandberg bluegrass

303 Bluebunch wheatgrass-western wheatgrass

304 Idaho fescue-bluebunch wheatgrass

305 Idaho fescue-Richardson needlegrass

306 Idaho fescue-slender wheatgrass

307 Idaho fescue-threadleaf sedge

308 Idaho fescue-tufted hairgrass

309 Idaho fescue-western wheatgrass

310 Needle-and-thread-blue grama

311 Rough fescue-bluebunch wheatgrass

312 Rough fescue-Idaho fescue

313 Tufted hairgrass-sedge

314 Big sagebrush-bluebunch wheatgrass

315 Big sagebrush-Idaho fescue

316 Big sagebrush-rough fescue

317 Bitterbrush-bluebunch wheatgrass

318 Bitterbrush-Idaho fescue

319 Bitterbrush-rough fescue

320 Black sagebrush-bluebunch wheatgrass

321 Black sagebrush-Idaho fescue

322 Curlleaf mountain-mahogany-bluebunch wheatgrass

323 Shrubby cinquefoil-rough fescue

324 Threetip sagebrush-Idaho fescue

401 Basin big sagebrush

402 Mountain big sagebrush

403 Wyoming big sagebrush

404 Threetip sagebrush

405 Black sagebrush

406 Low sagebrush

407 Stiff sagebrush

408 Other sagebrush types

409 Tall forb

410 Alpine rangeland

411 Aspen woodland

412 Juniper-pinyon woodland

413 Gambel oak

414 Salt desert shrub

415 Curlleaf mountain-mahogany

416 True mountain-mahogany

417 Littleleaf mountain-mahogany

418 Bigtooth maple

419 Bittercherry

420 Snowbrush

421 Chokecherry-serviceberry-rose

422 Riparian

501 Saltbush-greasewood

502 Grama-galleta

503 Arizona chaparral

504 Juniper-pinyon pine woodland

505 Grama-tobosa shrub

506 Creosotebush-bursage

507 Palo verde-cactus

508 Creosotebush-tarbush

509 Transition between oak-juniper woodland and mahogany-oak association

601 Bluestem prairie

602 Bluestem-prairie sandreed

603 Prairie sandreed-needlegrass

604 Bluestem-grama prairie

605 Sandsage prairie

606 Wheatgrass-bluestem-needlegrass

607 Wheatgrass-needlegrass

608 Wheatgrass-grama-needlegrass

609 Wheatgrass-grama

610 Wheatgrass

611 Blue grama-buffalo grass

612 Sagebrush-grass

613 Fescue grassland

614 Crested wheatgrass

615 Wheatgrass-saltgrass-grama

701 Alkali sacaton-tobosagrass

702 Black grama-alkali sacaton

703 Black grama-sideoats grama

704 Blue grama-western wheatgrass

705 Blue grama-galleta

706 Blue grama-sideoats grama

707 Blue grama-sideoats grama-black grama

708 Bluestem-dropseed

709 Bluestem-grama

710 Bluestem prairie

711 Bluestem-sacahuista prairie

712 Galleta-alkali sacaton

713 Grama-muhly-threeawn

714 Grama-bluestem

715 Grama-buffalo grass

716 Grama-feathergrass

717 Little bluestem-Indiangrass-Texas wintergrass

718 Mesquite-grama

719 Mesquite-liveoak-seacoast bluestem

720 Sand bluestem-little bluestem (dunes)

721 Sand bluestem-little bluestem (plains)

722 Sand sagebrush-mixed prairie

723 Sea oats

724 Sideoats grama-New Mexico feathergrass-winterfat

725 Vine mesquite-alkali sacaton

726 Cordgrass

727 Mesquite-buffalo grass

728 Mesquite-granjeno-acacia

729 Mesquite

730 Sand shinnery oak

731 Cross timbers-Oklahoma

732 Cross timbers-Texas (little bluestem-post oak)

733 Juniper-oak

734 Mesquite-oak

735 Sideoats grama-sumac-juniper

801 Savanna

802 Missouri prairie

803 Missouri glades

804 Tall fescue

805 Riparian

806 Gulf Coast salt marsh

807 Gulf Coast fresh marsh


901 Alder

902 Alpine herb

903 Beach wildrye-mixed forb

904 Black spruce-lichen

905 Bluejoint reedgrass

906 Broadleaf forest

907 Dryas

908 Fescue

909 Freshwater marsh

910 Hairgrass

911 Lichen tundra

912 Low scrub shrub birch-ericaceous

913 Low scrub swamp

914 Mesic sedge-grass-herb meadow tundra

915 Mixed herb-herbaceous

916 Sedge-shrub tundra

917 Tall shrub swamp

918 Tussock tundra

919 Wet meadow tundra

920 White spruce-paper birch

921 Willow


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Habitat: Cover Types

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the terms: cover, swamp


1 Jack pine

5 Balsam fir

12 Black spruce

13 Black spruce-tamarack

14 Northern pin oak

15 Red pine

16 Aspen

17 Pin cherry

18 Paper birch

19 Gray birch-red maple

20 White pine-northern red oak-red maple

21 Eastern white pine

22 White pine-hemlock

23 Eastern hemlock

24 Hemlock-yellow birch

25 Sugar maple-beech-yellow birch

26 Sugar maple-basswood

27 Sugar maple

28 Black cherry-maple

30 Red spruce-yellow birch

31 Red spruce-sugar maple-beech

32 Red spruce

33 Red spruce-balsam fir

34 Red spruce-Fraser fir

35 Paper birch-red spruce-balsam fir

37 Northern white-cedar

38 Tamarack

39 Black ash-American elm-red maple

40 Post oak-blackjack oak

42 Bur oak

43 Bear oak

44 Chestnut oak

45 Pitch pine

46 Eastern redcedar

50 Black locust

51 White pine-chestnut oak

52 White oak-black oak-northern red oak

53 White oak

55 Northern red oak

57 Yellow-poplar

58 Yellow-poplar-eastern hemlock

59 Yellow-poplar-white oak-northern red oak

60 Beech-sugar maple

61 River birch-sycamore

62 Silver maple-American elm

63 Cottonwood

64 Sassafras-persimmon

65 Pin oak-sweetgum

66 Ashe juniper-redberry (Pinchot) juniper

67 Mohrs (shin) oak

68 Mesquite

70 Longleaf pine

71 Longleaf pine-scrub oak

72 Southern scrub oak

73 Southern redcedar

74 Cabbage palmetto

75 Shortleaf pine

76 Shortleaf pine-oak

78 Virginia pine-oak

79 Virginia pine

80 Loblolly pine-shortleaf pine

81 Loblolly pine

82 Loblolly pine-hardwood

83 Longleaf pine-slash pine

84 Slash pine

85 Slash pine-hardwood

87 Sweetgum-yellow-poplar

88 Willow oak-water oak-diamondleaf (laurel) oak

89 Live oak

91 Swamp chestnut oak-cherrybark oak

92 Sweetgum-willow oak

93 Sugarberry-American elm-green ash

94 Sycamore-sweetgum-American elm

95 Black willow

96 Overcup oak-water hickory

97 Atlantic white-cedar

98 Pond pine

100 Pondcypress

101 Baldcypress

102 Baldcypress-tupelo

103 Water tupelo-swamp tupelo

104 Sweetbay-swamp tupelo-redbay

107 White spruce

108 Red maple

109 Hawthorn

110 Black oak

201 White spruce

202 White spruce-paper birch

203 Balsam poplar

204 Black spruce

205 Mountain hemlock

206 Engelmann spruce-subalpine fir

207 Red fir

208 Whitebark pine

209 Bristlecone pine

210 Interior Douglas-fir

211 White fir

212 Western larch

213 Grand fir

215 Western white pine

216 Blue spruce

217 Aspen

218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

221 Red alder

222 Black cottonwood-willow

223 Sitka spruce

224 Western hemlock

225 Western hemlock-Sitka spruce

226 Coastal true fir-hemlock

227 Western redcedar-western hemlock

228 Western redcedar

229 Pacific Douglas-fir

230 Douglas-fir-western hemlock

231 Port-Orford-cedar

232 Redwood

233 Oregon white oak

234 Douglas-fir-tanoak-Pacific madrone

235 Cottonwood-willow

236 Bur oak

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

240 Arizona cypress

241 Western live oak

242 Mesquite

243 Sierra Nevada mixed conifer

244 Pacific ponderosa pine-Douglas-fir

245 Pacific ponderosa pine

246 California black oak

247 Jeffrey pine

248 Knobcone pine

249 Canyon live oak

250 Blue oak-foothills pine

251 White spruce-aspen

252 Paper birch

253 Black spruce-white spruce

254 Black spruce-paper birch

255 California coast live oak

256 California mixed subalpine


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Habitat: Plant Associations

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the terms: bog, shrub


K001 Spruce-cedar-hemlock forest

K002 Cedar-hemlock-Douglas-fir forest

K003 Silver fir-Douglas-fir forest

K004 Fir-hemlock forest

K005 Mixed conifer forest

K006 Redwood forest

K007 Red fir forest

K008 Lodgepole pine-subalpine forest

K009 Pine-cypress forest

K010 Ponderosa shrub forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K013 Cedar-hemlock-pine forest

K014 Grand fir-Douglas-fir forest

K015 Western spruce-fir forest

K016 Eastern ponderosa forest

K017 Black Hills pine forest

K018 Pine-Douglas-fir forest

K020 Spruce-fir-Douglas-fir forest

K021 Southwestern spruce-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K025 Alder-ash forest

K026 Oregon oakwoods

K028 Mosaic of K002 and K026

K029 California mixed evergreen forest

K030 California oakwoods

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K033 Chaparral

K034 Montane chaparral

K035 Coastal sagebrush

K036 Mosaic of K030 and K035

K037 Mountain-mahogany-oak scrub

K038 Great Basin sagebrush

K039 Blackbrush

K040 Saltbush-greasewood

K041 Creosote bush

K042 Creosote bush-bur sage

K043 Paloverde-cactus shrub

K044 Creosote bush-tarbush

K045 Ceniza shrub

K047 Fescue-oatgrass

K048 California steppe

K049 Tule marshes

K050 Fescue-wheatgrass

K051 Wheatgrass-bluegrass

K052 Alpine meadows and barren

K053 Grama-galleta steppe

K054 Grama-tobosa prairie

K055 Sagebrush steppe

K056 Wheatgrass-needlegrass shrubsteppe

K057 Galleta-threeawn shrubsteppe

K058 Grama-tobosa shrubsteppe

K059 Trans-Pecos shrub savanna

K060 Mesquite savanna

K061 Mesquite-acacia savanna

K062 Mesquite-live oak savanna

K063 Foothills prairie

K064 Grama-needlegrass-wheatgrass

K065 Grama-buffalo grass

K066 Wheatgrass-needlegrass

K067 Wheatgrass-bluestem-needlegrass

K068 Wheatgrass-grama-buffalo grass

K069 Bluestem-grama prairie

K070 Sandsage-bluestem prairie

K071 Shinnery

K072 Sea oats prairie

K073 Northern cordgrass prairie

K074 Bluestem prairie

K075 Nebraska Sandhills prairie

K076 Blackland prairie

K077 Bluestem-sacahuista prairie

K078 Southern cordgrass prairie

K081 Oak savanna

K082 Mosaic of K074 and K100

K083 Cedar glades

K084 Cross Timbers

K085 Mesquite-buffalo grass

K086 Juniper-oak savanna

K087 Mesquite-oak savanna

K088 Fayette prairie

K089 Black Belt

K090 Live oak-sea oats

K093 Great Lakes spruce-fir forest

K094 Conifer bog

K095 Great Lakes pine forest

K096 Northeastern spruce-fir forest

K097 Southeastern spruce-fir forest

K098 Northern floodplain forest

K099 Maple-basswood forest

K100 Oak-hickory forest

K101 Elm-ash forest

K102 Beech-maple forest

K103 Mixed mesophytic forest

K104 Appalachian oak forest

K106 Northern hardwoods

K107 Northern hardwoods-fir forest

K108 Northern hardwoods-spruce forest

K109 Transition between K104 and K106

K110 Northeastern oak-pine forest

K111 Oak-hickory-pine

K112 Southern mixed forest

K113 Southern floodplain forest

K114 Pocosin


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Habitat: Ecosystem

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):


FRES10 White-red-jack pine

FRES11 Spruce-fir

FRES12 Longleaf-slash pine

FRES13 Loblolly-shortleaf pine

FRES14 Oak-pine

FRES15 Oak-hickory

FRES16 Oak-gum-cypress

FRES17 Elm-ash-cottonwood

FRES18 Maple-beech-birch

FRES19 Aspen-birch

FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES22 Western white pine

FRES23 Fir-spruce

FRES24 Hemlock-Sitka spruce

FRES25 Larch

FRES26 Lodgepole pine

FRES27 Redwood

FRES28 Western hardwoods

FRES29 Sagebrush

FRES30 Desert shrub

FRES31 Shinnery

FRES32 Texas savanna

FRES33 Southwestern shrubsteppe

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES36 Mountain grasslands

FRES37 Mountain meadows

FRES38 Plains grasslands

FRES39 Prairie

FRES40 Desert grasslands

FRES41 Wet grasslands

FRES42 Annual grasslands

FRES44 Alpine


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In Great Britain and/or Ireland:
Foodplant / parasite
sporangium of Bremia lactucae parasitises live leaf of Sonchus arvensis
Remarks: season: 9-10
Other: unusual host/prey

Foodplant / parasite
telium of Coleosporium tussilaginis parasitises live Sonchus arvensis

Foodplant / feeds on
pycnidium of Diplodina coelomycetous anamorph of Diplodina sonchi feeds on Sonchus arvensis
Remarks: season: 8

Foodplant / internal feeder
larva of Ensina sonchi feeds within capitulum of Sonchus arvensis

Foodplant / parasite
Golovinomyces cichoracearum parasitises live Sonchus arvensis

Foodplant / sap sucker
Hyperomyzus lactucae sucks sap of live Sonchus arvensis

Foodplant / parasite
telium of Miyagia pseudosphaeria parasitises live stem of Sonchus arvensis

Foodplant / spot causer
amphigenous colony of Ramularia hyphomycetous anamorph of Mycosphaerella hieracii causes spots on live leaf of Sonchus arvensis

Foodplant / internal feeder
larva of Paroxyna producta feeds within capitulum of Sonchus arvensis
Remarks: Other: uncertain

Foodplant / spot causer
Spermosporina anamorph of Spermosporina sonchi-oleracei causes spots on live leaf of Sonchus arvensis

Foodplant / open feeder
nocturnal larva of Tenthredo pseudorossi grazes on leaf of Sonchus arvensis
Other: sole host/prey

Foodplant / false gall
larva of Tephritis formosa causes swelling of capitulum of Sonchus arvensis

Foodplant / internal feeder
larva of Trupanea amoena feeds within capitulum of Sonchus arvensis
Remarks: Other: uncertain


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General Ecology

Broad-scale Impacts of Plant Response to Fire

More info for the terms: cover, density, marsh, mesic, phenology, prescribed burn, prescribed fire, restoration, swale, wildfire

Perennial sowthistle may establish on burned sites from wind-dispersed seed.
Soil samples were taken from burned and unburned areas of a 270-year-old red
pine forest in Minnesota 3 years after wildfire. No perennial sowthistle
germinants emerged from soil taken from unburned areas, while the equivalent of
109,000 perennial sowthistle seedlings per hectare emerged from soil taken from
burned areas. No perennial sowthistle plants occurred in either burned or
unburned plots, and no perennial sowthistle seeds were found in unburned soil
samples. The author concluded that perennial sowthistle seedlings probably
developed from seeds blown into the burned areas after the fire [3].

Probability of postfire establishment from offsite seed sources may be related
to season of burning. Thompson and Shay [120] conducted 3 prescribed burn
treatments in 3 different seasons on the Delta Marsh in Manitoba. Perennial
sowthistle was absent from unburned plots, but seedlings established on
both summer and fall burned plots, with greatest establishment 1 month following summer
burns. These seedlings persisted into the following year, resulting in increased
nonseedling shoot density and biomass on summer burned plots:

Mean values (95% CI) for 3 variables of
perennial sowthistle following burning during different seasons at the Delta
Marsh, Manitoba [120]

Plot type/burn date/sample date

ControlAugust 1979 burn, sampled September 1979August 1979 burn, sampled August 1980October 1979 burn, sampled August 1980May 1980 burn, sampled August 1980
Seedling density (no./m²)015.5 (11.5)00.4 (0.4)0
Nonseedling shoot density (no./m²)0---8 (1.7)00
Biomass (g/m²)0---28.2 (16.9)0.1 (0.2)0

Perennial sowthistle has a long flowering period that begins in early July and
continues until plants are frosted, with peak flowering in mid to late summer
[110]. Summer burns on the Delta Marsh were conducted at the time of year when
the most mature sowthistle seed was likely being dispersed, while timing of fall
burns corresponded to a time of year when fewer seeds were likely to be
available, and spring burns occurred when no perennial sowthistle seed would
likely be available [120]. Although there is evidence that perennial sowthistle
seeds occur in the soil seed bank in the Delta Marsh [88] (see
seed banking
), it is more likely that perennial sowthistle seedlings
detected in this study [120] established from wind-dispersed seed, given the
correspondence of burn season, perennial sowthistle phenology, and seedling establishment.

While perennial sowthistle is likely to persist after
fire, data are insufficient for detecting trends in its postfire abundance. Simulated "light" and "deep" burns using a propane
torch in both bluejoint reedgrass and willow savanna habitats in northern
Alberta found little difference in perennial sowthistle cover 2 growing seasons after
summer burning

Mean percent cover (SE) of perennial sowthistle following
experimental burn treatments in 2 community types in Alberta [59]

Plant community

Burn treatment
Bluejoint reedgrass meadow1 (1)2 (1)4 (2)
Willow savanna10 (3)15 (5)15 (4)

Abundance of perennial sowthistle plants was highly variable on burned and
unburned prairie sites in a study to evaluate the effects of prescribed burning
on grassland species desired for wildlife habitat on the Tewaukon National Wildlife Refuge in
southeastern North Dakota. Cover of perennial sowthistle was mostly the same
on burned and unburned sites, but in some years was either significantly higher
on or significantly lower on burned versus control plots. Data show both
great variation in percent canopy cover and no clear trend of increase or
decrease on burned versus control plots, 1 month or 26 months after fires in May
or June [86].

In northwestern Minnesota, flowering of perennial sowthistle increased on
some sites after
prescribed fire was used as part of a prairie restoration project. Burns were
conducted in spring 1973, and data on flowering response were collected during
the growing season of the same year. Results were based on comparison of burned and unburned transects.
Perennial sowthistle was recorded on 3 site types in the study area: a wet-mesic
site in "badly" disturbed prairie, a wet swale site
in undisturbed prairie, and a gently
sloping to nearly level mesic site in undisturbed prairie. Flowering increased
after prescribed fire, relative to controls, on both disturbed and undisturbed wet prairie sites, but was not different from
controls in the mesic prairie site [91].


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Plant Response to Fire

More info for the term: marsh

Perennial sowthistle can establish on burned sites from wind-dispersed seed, as suggested by results of studies in red pine (Pinus resinosa) forest in Minnesota [3] and on the Delta Marsh in Manitoba [120]. Perennial sowthistle seedlings may be more likely to establish on burned sites after summer fires, when perennial sowthistle plants are likely to be dispersing seed, than following fall or spring fires [120].

Established perennial sowthistle plants are likely to persist after fire on burned sites, though it is unclear whether its overall abundance will increase or decrease in the postfire environment. Postfire data from studies in Alberta, Canada [59] and North Dakota [86] shows little difference between burned and unburned sites, and no detectable postfire trend in perennial sowthistle abundance 1 to 2 years after fire.

Flowering of perennial sowthistle may increase after fire. Postfire flowering response may be related to postfire moisture availability [91].


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Immediate Effect of Fire

More info for the term: high-severity fire

As of this writing (2004), no accounts in the literature discuss or describe immediate effects of fire on perennial sowthistle plants or seeds. It is reasonable to assume that perennial sowthistle plants are top-killed by fire and that some underground regenerating organs survive even high-severity fire (see Fire adaptations).


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Fire Ecology

More info for the terms: fuel, high-severity fire, marsh, shrub

Fire adaptations: As of this writing (2004), no information is available specifically addressing fire adaptations in perennial sowthistle; however, inferences regarding its ability to establish, persist, and spread after fire are possible, based on its regeneration strategies and data from a small number of fire studies in which perennial sowthistle occurred.

Perennial sowthistle seeds are dispersed by wind (see Seed dispersal), and seedlings may establish on burned areas from offsite seed sources when mature plants occur in the vicinity of the burn. Seedlings established on burned sites in red pine forest in Minnesota [3] and on the Delta Marsh in Manitoba [120], while no perennial sowthistle plants occurred on unburned control plots in either study. Probability of postfire establishment from offsite seed may be related to season of burning (see Plant Response to Fire). Information on seed banking for perennial sowthistle suggests that it is possible for seedlings to establish from the soil seed bank after fire, although this has not been documented in the available literature.

Perennial sowthistle plants are likely to survive and persist on burned areas, even after high-severity fire, and the limited available data on postfire response of perennial sowthistle indicate little difference in abundance between burned and unburned sites [59,86] (see Plant response to fire). Perennial sowthistle shoots develop from numerous underground buds on both vertical and horizontal roots, and on basal portions of aerial stems [51,89] (see Asexual regeneration). Vertical roots can be 5 to 10 feet (1.5-3 m) deep [10] with the potential to produce shoots from buds as deep as 16 inches (40 cm) below the soil surface [110]. These buds would not be affected by fire. Horizontal roots of perennial sowthistle occur 2 to 4 inches (5-10 cm) below the surface [10] and would probably also be protected from all but the most severe fires.

FIRE REGIMES: As of this writing (2004), no information regarding FIRE REGIMES in which perennial sowthistle evolved was found in the available literature; nor was information available regarding impacts of perennial sowthistle invasion on fuel characteristics or FIRE REGIMES in native North American plant communities. The following table provides fire return intervals for plant communities and ecosystems where perennial sowthistle may occur in North America. Perennial sowthistle may also occur within riparian or wetland areas included in these ecosystems. For additional information on these FIRE REGIMES, see the FEIS summary on the dominant species listed below:

Community or Ecosystem Dominant Species Fire Return Interval Range (years)
silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii > 200
grand fir Abies grandis 35-200 [6]
maple-beech-birch Acer-Fagus-Betula > 1,000
silver maple-American elm Acer saccharinum-Ulmus americana < 35 to 200
sugar maple Acer saccharum > 1,000
sugar maple-basswood Acer saccharum-Tilia americana > 1,000 [126]
California chaparral Adenostoma and/or Arctostaphylos spp. 87]
bluestem prairie Andropogon gerardii var. gerardii-Schizachyrium scoparium < 10 [68,87]
Nebraska sandhills prairie Andropogon gerardii var. paucipilus-Schizachyrium scoparium < 10
bluestem-Sacahuista prairie Andropogon littoralis-Spartina spartinae 87]
silver sagebrush steppe Artemisia cana 5-45 [56,96,130]
sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [87]
basin big sagebrush Artemisia tridentata var. tridentata 12-43 [101]
mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [8,22,80]
Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [124,131]
coastal sagebrush Artemisia californica  
saltbush-greasewood Atriplex confertifolia-Sarcobatus vermiculatus  
desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 [87]
plains grasslands Bouteloua spp. < 35 [87,130]
blue grama-needle-and-thread grass-western wheatgrass Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii < 35 [87,100,130]
blue grama-buffalo grass Bouteloua gracilis-Buchloe dactyloides 87,130]
grama-galleta steppe Bouteloua gracilis-Pleuraphis jamesii < 35 to < 100
blue grama-tobosa prairie Bouteloua gracilis-Pleuraphis mutica 87]
cheatgrass Bromus tectorum 95,128]
California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [87]
sugarberry-America elm-green ash Celtis laevigata-Ulmus americana-Fraxinus pennsylvanica 126]
paloverde-cactus shrub Cercidium microphyllum/Opuntia spp. 87]
curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [9,103]
mountain-mahogany-Gambel oak scrub Cercocarpus ledifolius-Quercus gambelii 87]
Atlantic white-cedar Chamaecyparis thyoides 35 to > 200 [126]
blackbrush Coleogyne ramosissima < 35 to < 100
Arizona cypress Cupressus arizonica < 35 to 200
northern cordgrass prairie Distichlis spicata-Spartina spp. 1-3 [87]
beech-sugar maple Fagus spp.-Acer saccharum > 1,000 [126]
California steppe Festuca-Danthonia spp. 87,115]
black ash Fraxinus nigra < 35 to 200
juniper-oak savanna Juniperus ashei-Quercus virginiana < 35
Ashe juniper Juniperus ashei < 35
western juniper Juniperus occidentalis 20-70
Rocky Mountain juniper Juniperus scopulorum 87]
cedar glades Juniperus virginiana 3-22 [49,87]
tamarack Larix laricina 35-200 [87]
western larch Larix occidentalis 25-350 [13,29]
creosotebush Larrea tridentata < 35 to < 100
Ceniza shrub Larrea tridentata-Leucophyllum frutescens-Prosopis glandulosa 87]
yellow-poplar Liriodendron tulipifera 126]
wheatgrass plains grasslands Pascopyrum smithii 87,96,130]
Great Lakes spruce-fir Picea-Abies spp. 35 to > 200
northeastern spruce-fir Picea-Abies spp. 35-200 [35]
southeastern spruce-fir Picea-Abies spp. 35 to > 200 [126]
Engelmann spruce-subalpine fir Picea engelmannii-Abies lasiocarpa 35 to > 200 [6]
black spruce Picea mariana 35-200
conifer bog* Picea mariana-Larix laricina 35-200 [35]
blue spruce* Picea pungens 35-200 [6]
red spruce* Picea rubens 35-200 [35]
pine-cypress forest Pinus-Cupressus spp. 6]
pinyon-juniper Pinus-Juniperus spp. 87]
whitebark pine* Pinus albicaulis 50-200 [2,4]
jack pine Pinus banksiana 35]
Mexican pinyon Pinus cembroides 20-70 [82,117]
Rocky Mountain lodgepole pine* Pinus contorta var. latifolia 25-340 [12,13,119]
Sierra lodgepole pine* Pinus contorta var. murrayana 35-200 [6]
shortleaf pine Pinus echinata 2-15
shortleaf pine-oak Pinus echinata-Quercus spp. 126]
Colorado pinyon Pinus edulis 10-400+ [39,43,87]
slash pine Pinus elliottii 3-8
slash pine-hardwood Pinus elliottii-variable 126]
Jeffrey pine Pinus jeffreyi 5-30
western white pine* Pinus monticola 50-200 [6]
longleaf-slash pine Pinus palustris-P. elliottii 1-4 [85,126]
longleaf pine-scrub oak Pinus palustris-Quercus spp. 6-10 [126]
Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [6]
interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30  [6,11,73]
Arizona pine Pinus ponderosa var. arizonica 2-15 [11,25,104]
Table Mountain pine Pinus pungens 126]
red pine (Great Lakes region) Pinus resinosa 10-200 (10**) [35,40]
red-white-jack pine* Pinus resinosa-P. strobus-P. banksiana 10-300 [35,54]
pitch pine Pinus rigida 6-25 [21,55]
pocosin Pinus serotina 3-8
pond pine Pinus serotina 3-8
eastern white pine Pinus strobus 35-200
eastern white pine-eastern hemlock Pinus strobus-Tsuga canadensis 35-200
eastern white pine-northern red oak-red maple Pinus strobus-Quercus rubra-Acer rubrum 35-200
loblolly pine Pinus taeda 3-8
loblolly-shortleaf pine Pinus taeda-P. echinata 10 to < 35
Virginia pine Pinus virginiana 10 to < 35
Virginia pine-oak Pinus virginiana-Quercus spp. 10 to < 35
sycamore-sweetgum-American elm Platanus occidentalis-Liquidambar styraciflua-Ulmus americana 126]
galleta-threeawn shrubsteppe Pleuraphis jamesii-Aristida purpurea < 35 to < 100
eastern cottonwood Populus deltoides 87]
aspen-birch Populus tremuloides-Betula papyrifera 35-200 [35,126]
quaking aspen (west of the Great Plains) Populus tremuloides 7-120 [6,47,79]
mesquite Prosopis glandulosa < 35 to < 100 [78,87]
mesquite-buffalo grass Prosopis glandulosa-Buchloe dactyloides < 35
Texas savanna Prosopis glandulosa var. glandulosa < 10
black cherry-sugar maple Prunus serotina-Acer saccharum > 1,000 [126]
mountain grasslands Pseudoroegneria spicata 3-40 (10**) [5,6]
Rocky Mountain Douglas-fir* Pseudotsuga menziesii var. glauca 25-100 [6,7,8]
coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240  [6,83,99]
California mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii < 35
California oakwoods Quercus spp. 6]
oak-hickory Quercus-Carya spp. 126]
oak-juniper woodland (Southwest) Quercus-Juniperus spp. < 35 to < 200 [87]
northeastern oak-pine Quercus-Pinus spp. 10 to 126]
oak-gum-cypress Quercus-Nyssa-spp.-Taxodium distichum 35 to > 200 [85]
southeastern oak-pine Quercus-Pinus spp. 126]
coast live oak Quercus agrifolia 2-75 [46]
white oak-black oak-northern red oak Quercus alba-Q. velutina-Q. rubra 126]
canyon live oak Quercus chrysolepis <35 to 200
blue oak-foothills pine Quercus douglasii-P. sabiniana 6]
northern pin oak Quercus ellipsoidalis 126]
Oregon white oak Quercus garryana 6]
bear oak Quercus ilicifolia 126]
California black oak Quercus kelloggii 5-30 [87]
bur oak Quercus macrocarpa 126]
oak savanna Quercus macrocarpa/Andropogon gerardii-Schizachyrium scoparium 2-14 [87,126]
shinnery Quercus mohriana 87]
chestnut oak Quercus prinus 3-8
northern red oak Quercus rubra 10 to < 35
post oak-blackjack oak Quercus stellata-Q. marilandica < 10
black oak Quercus velutina < 35
live oak Quercus virginiana 10 to126]
interior live oak Quercus wislizenii 6]
cabbage palmetto-slash pine Sabal palmetto-Pinus elliottii < 10 [85,126]
blackland prairie Schizachyrium scoparium-Nassella leucotricha < 10
Fayette prairie Schizachyrium scoparium-Buchloe dactyloides 126]
little bluestem-grama prairie Schizachyrium scoparium-Bouteloua spp. < 35
tule marshes Scirpus and/or Typha spp. 87]
redwood Sequoia sempervirens 5-200 [6,38,116]
southern cordgrass prairie Spartina alterniflora 1-3 [87]
baldcypress Taxodium distichum var. distichum 100 to > 300
pondcypress Taxodium distichum var. nutans 85]
western redcedar-western hemlock Thuja plicata-Tsuga heterophylla > 200 [6]
eastern hemlock-yellow birch Tsuga canadensis-Betula alleghaniensis > 200 [126]
western hemlock-Sitka spruce Tsuga heterophylla-Picea sitchensis > 200
mountain hemlock* Tsuga mertensiana 35 to > 200 [6]
elm-ash-cottonwood Ulmus-Fraxinus-Populus spp. < 35 to 200 [35,126]
*fire return interval varies widely; trends in variation are noted in the species review


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Successional Status

More info on this topic.

More info for the terms: eruption, succession

Perennial sowthistle is an early-successional plant. Komarova [67] and Zollinger and Parker [133] describe perennial sowthistle as a pioneer species. In a study of succession after fire in "highland hardwoods" in Wisconsin, it appeared in 6 out of 10 plots in the herbaceous stage of succession [44]. Although infrequent, perennial sowthistle is part of the early successional community on wetlands in the blast zone after the Mount St. Helen's eruption [121].

Perennial sowthistle is most competitive under abundant precipitation and moderate climates [133].


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Regeneration Processes

More info for the terms: cover, fresh, litter, marsh, natural, pappus, perfect, radicle, series

Perennial sowthistle can reproduce by seed and vegetatively [10,30,110].

Breeding system: Perennial sowthistle flowers are perfect [31] and generally self-incompatible [31,110].

Pollination: Perennial sowthistle is pollinated by insects including honeybees and other bees, hover flies, and blister beetles [31,110].

Seed production: Perennial sowthistle can produce large numbers of seeds [31,53,110,112]. Seeds produced by self pollination are generally nonviable and smaller than those produced by cross-pollination [31,110].

Heads contain many fertile flowers but the number of achenes produced varies widely among heads, plants, and locality. Variability likely results from several factors, including environmental conditions and availability of pollinators [110].

Perennial sowthistle can typically produce an average of 30 achenes per head and up to 50,000/yd2 [110]. In North Dakota, 1 main stalk, with "relatively little competition", produced 62 heads and 9,750 well-developed achenes. The author collected seeds from the plant for a 30-day period [112]. In South Dakota, artificially cross-pollinated heads from greenhouse- and field-grown plants produced about 50 achenes per head, but number of achenes per head in natural populations varied from about 20 to 40 or from 60 to 80, depending upon the year [31].

Seed dispersal: Seeds of perennial sowthistle are mostly wind dispersed [28,53,110], but other dispersal agents may play a minor role. The pappus, attached to the seed, aids in wind dispersal [92]. Hume and Archibold [63] placed seed traps at varying distances from a "weedy" field in Saskatchewan. Results show wind-blown seeds of perennial sowthistle can disperse at least 110 yards (100 m). They do not report wind speed.

Sheldon and Burrows [105] conducted experiments to determine maximum dispersal distance of perennial sowthistle seeds at differing wind speeds. They used perennial sowthistle plants with a mean height of 3 feet (90 cm). They observed a maximum dispersal distance of 11 yards (10 m).

Wind speed (km/hour) 5.47 10.94 16.41
Dispersal distance (m) 3.34 6.67 10.00

In addition to wind dispersal, seeds of perennial sowthistle may be dispersed by birds and other animals. Martin and others (as reported in [133], a literature review) state perennial sowthistle is a minor element in the diet of some North American birds, and some seeds may germinate after ingestion and excretion by birds and animals. Hooked cells at the tips of pappus hairs allow the pappus to cling to clothes and animal hairs and aid in seed dispersal [110,133].

Seed banking: While viable perennial sowthistle seeds have been found in the seed banks of marshes and wetlands [60,88], longevity of seeds in the soil seed bank under field conditions of these communities is unknown. A study of perennial sowthistle seed dormancy suggests that some seed may remain viable for 3 or more years in cultivated soils [23].

Seed banking studies in the Delta Marsh, Manitoba, suggest that viable perennial sowthistle seeds occur in marsh habitats. Sowthistles (Sonchus spp.) were dominant in the drier upland areas, so seed was likely dispersed throughout the marsh. Perennial sowthistle seedlings emerged from soil samples taken from the marsh and exposed to "drawdown" conditions (soil surface kept moist), but not from samples exposed to "submersed" conditions (continuously flooded to a depth of 2 to 3 cm above the soil surface) [88].

In an experiment designed to test seedling emergence from boreal wetland soils under changing climatic conditions, perennial sowthistle seedlings emerged from the soil seed bank in willow (Salix spp.) savanna and bluejoint reedgrass vegetation zones of a mid-boreal wetland in Alberta [60].

Although seeds of perennial sowthistle have low viability in cultivated fields, some can remain dormant but viable for more than 3 years in cultivated soil. Chepil [23] conducted 3 separate seed dormancy tests for "weed" species in cultivated soil in Saskatchewan. In the 1st experiment an indefinite number of perennial sowthistle seeds was planted in 3 soil types on 18 September, 1937. Introduction of seeds from other sources was prevented. No seeds were planted greater than 3 inches (7.6 cm) deep. Number of viable seeds remaining in the soil after 3 years was determined by repeated germination tests in the laboratory until no more germination occurred. Results are shown in the table below [23]:

Percentage of perennial sowthistle seeds germinated each year after planting in 3 soil types in 1937 [23]
Soil texture 1938 1939 1940 Viable seeds remaining
Clay 43.3 16.2 2.7 37.8
Loam 66.7 13.3 0 20.0
Sandy loam 86.7 0 3.3 10.0

In the 2nd experiment, 50 perennial sowthistle seeds were planted no deeper than 3 inches (7.6 cm) on 14 October, 1938, in 3 soil types. Again, number of viable seeds remaining in the soil after 6 years was determined by repeated germination tests in the laboratory until no more germination occurred. Values given are number of viable seeds [23].

Soil texture 1939 1940 1941 1942 1943 1944 Viable seeds remaining
Clay 33 0 4 0 0 0 0
Loam 1 0 0 0 0 0 0
Sandy loam 2 3 0 0 0 0 1

The 3rd experiment utilized 1,000 perennial sowthistle seeds planted no deeper than 3 inches (7.6 cm). Seeds were planted between 1 and 5 November, 1940, in 3 soil types and only seeds germinated in the field were counted. Numbers are actual seeds germinating, not percentages [23].

Soil texture 1941 1942 1943 1944 1945
Clay 18 0 2 5 0
Loam 16 0 0 0 0
Sandy loam 12 0 0 1 0

Clay appears to be most conducive to long-term viability of perennial sowthistle seeds [23] (See Site Characteristics).

Germination: Germination of perennial sowthistle seeds increases with both increasing soil temperature and time since flowering. Perennial sowthistle seed in the field begins to germinate when the soil has "warmed" [74].

Seeds may be capable of germination about 5 days after pollination [74]; however, germination rates increased from low to none 4 days after flowering to a maximum 7 to 9 days after flowering [31,66,110]. In field germination experiments in South Dakota, Derscheid and Schultz [31] noted that percentage of viable seeds produced by perennial sowthistle ranged from 10% 6 days after blooming to 89% 9 days after blooming. If perennial sowthistle plants are pulled or cut and placed in a pile it is possible for viable seeds to be produced if flowers are present when the plants are cut [110].

In laboratory germination tests, perennial sowthistle seed viability is "relatively" high. Kinch and Termunde [66] achieved 95% germination in the laboratory using "well-matured" seed.

Orientation of perennial sowthistle seeds in the soil profile is important to germination, and light may stimulate germination. Bosy and Aarssen [15] conducted seed germination tests on perennial sowthistle using agar as a germinating medium. Agar was used to eliminate any environmental differences at a given depth and enabled the authors to maintain seed orientation. They found surface-lying seeds of perennial sowthistle displayed higher germination than buried seeds [15]. Germination was 50% for seeds germinated in soil and 80% for seeds germinated on moist filter paper, and germination was higher in diffuse laboratory light than in complete darkness [90]. When seeds were buried, seeds oriented with the radicle horizontal had significantly greater (P<0.05) germination than seeds with the radicle oriented either upward or downward.

Studies indicate temperatures from 77 to 86 °F (25-30 °C) are optimal for germination. Seeds germinate poorly (<5%) below 68 °F (20 °C) and above 95 °F (35 °C), but alternating temperatures were more favorable for germination than constant temperatures if temperatures above 77 °F (25 °C) are included in the cycle [52]. Stevens [110] reports seeds exposed to 90 °F (32 °C) for a "few hours daily" germinate "freely" in 4 to 7 days.

Perennial sowthistle seed germination in wetlands could be limited by saturated soils. For example, Hogenbirk and Wein [60] germinated seeds of perennial sowthistle from combined soil and litter samples from a mid-boreal wetland in Alberta. No perennial sowthistle seeds germinated in samples taken from a sedge (Carex spp.) marsh. Perennial sowthistle seeds stored in fresh water were 100% decomposed after 3 months storage [18].

Seedling establishment/growth: Perennial sowthistle seedlings survive best in areas with protective plant cover or litter and high moisture compared with open cultivated soil [110]. Accordingly, seedlings are often only found along pond, ditch, or field margins, or in lawns, meadows, or uncultivated fields [92]. In a series of field germination experiments with perennial sowthistle seeds, Stevens [110] had little success growing seedlings in cultivated field plots. Laboratory germination tests with the same lot of seeds showed 56% germination.

Most perennial sowthistle seedlings do not emerge until mid- to late May in Saskatchewan and the Great Plains of the United States [74]. Seedlings grow slowly for about the first 2 weeks until leaves are about 1.2 inches (3 cm) long [110]. They develop rapidly after that, and reproductive ability of spreading roots is established quickly [52,110]. Stevens [110] noted 10 seedlings on 17 May, 1923. The 10 seedlings grew slowly until 1 June when the largest leaves were 1.2 inches (3 cm) long. After that, they developed "rapidly" and on 5 July, a horizontal root 28 inches long (71 cm) was removed from the largest plant [110].

Most seedlings do not flower the first year, but flowering in late summer is possible from some first-year seedlings in favorable environments [52,110].

Asexual regeneration: Perennial sowthistle reproduces vegetatively from buds on horizontal and vertical roots and on basal portions of aerial stems located just under the soil surface. Thickened roots develop as a result of secondary growth of original fibrous roots [51] and begin to show reproductive capacity when thickened to 1 to 1.5 mm [50]. This occurs on vertical primary roots when seedlings reach the 4-leaf stage and on horizontal roots when seedlings have 6 to 7 photosynthetic leaves. One-month-old seedlings can have 7 to 8 leaves with horizontal roots from 4 to 6 inches (10-15 cm) long and 1.5 mm thick. Horizontal roots from 24 to 39 inches (60-100 cm) and vertical roots penetrating 20 inches (50 cm) can develop from seedlings within 4 months after emergence. Vertical roots can produce vegetative buds as deep as 20 inches (50 cm) below the soil surface, and new aerial growth has been observed from buds as deep as 16 inches (40 cm) below the soil surface [110]. New shoots can develop from buds that overwinter on both vertical and horizontal "spreading" roots, and/or on basal portions of aerial stems [51,89]. In North Dakota, the rate of vegetative spread of perennial sowthistle clones varied from 1.6 to 9 feet (0.5-2.8 m) per year, depending on the clone (personal observation in [74]).

Harris and Shorthouse [53] describe the horizontal roots of perennial sowthistle as "easily broken", and new plants can grow from root fragments and flower within 1 year [50,110]. Of perennial sowthistle root fragments planted on 3 May in a field experiment in North Dakota, approximately 50% of 0.25-inch-long pieces, 75% of 0.5-inch-long pieces, and 85% of 1-inch-long pieces produced plants within 20 to 34 days. Where well developed buds were present on root fragments, plants emerged quickly and were strong; if buds were not present, new plants grew more slowly from the cut surface and were weak. Plants grown from these root fragments reached a height of 3 feet (1 m) and flowered abundantly between 27 July and 6 August. On 29 June the largest of these plants had 2 horizontal roots 42 to 45 inches long (107-114 cm). The 45-inch root had 42 buds and sprouts in various stages of development. By the end of the growing season, horizontal roots from these plants reached about 6 feet (1.8 m) in length [110].


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Growth Form (according to Raunkiær Life-form classification)

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More info for the term: hemicryptophyte



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Life Form

More info for the term: forb



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Molecular Biology and Genetics

Molecular Biology

Barcode data: Sonchus arvensis

The following is a representative barcode sequence, the centroid of all available sequences for this species.

Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)


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Statistics of barcoding coverage: Sonchus arvensis

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 6
Specimens with Barcodes: 19
Species With Barcodes: 1
Creative Commons Attribution 3.0 (CC BY 3.0)

© Barcode of Life Data Systems

Source: Barcode of Life Data Systems (BOLD)


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Conservation Status

National NatureServe Conservation Status


Rounded National Status Rank: NNA - Not Applicable

United States

Rounded National Status Rank: NNA - Not Applicable

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© NatureServe

Source: NatureServe


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NatureServe Conservation Status

Rounded Global Status Rank: GNR - Not Yet Ranked

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

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Source: NatureServe


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Impacts and Control

More info for the terms: competition, fire management, frequency, invasive species, natural

Impacts: Information concerning the impacts of perennial sowthistle on natural communities is absent from the literature. Research is needed to determine and document what effects perennial sowthistle may have on wildlands.

Control: Perennial sowthistle is relatively resistant to many common broadleaf herbicides compared to most annual broadleaf weeds. Consequently, the best systems for control often include a combination of cultural and chemical treatments designed to reduce competition from perennial sowthistle, prevent seed production, and reduce the reproductive capacity of its roots (Fryer and Makepeace, 1982, as reported in a literature review [74]).

As of this writing (2004) there is no information available on control of perennial sowthistle in natural areas.

Prevention: The most efficient and effective method of managing invasive species is to prevent their invasion and spread [107]. Since perennial sowthistle seed is so easily disseminated by wind, scouting and detection are keys to preventing plant establishment [133]. It is easier to prevent initial colonization by perennial sowthistle than to eliminate established populations. Seedlings are easily controlled through mechanical and chemical methods. Planting weed-free crop seed and controlling perennial sowthistle on field borders can prevent initial infestations in wildlands adjacent to agricultural settings [133] (See Seedling establishment/growth).

Integrated management: Components of any integrated weed management program are sustained effort, constant evaluation, and the adoption of improved strategies [106]. Factors to be addressed before a management decision is made include inventory and assessment to identify the target weed(s) and determine the size of the infestation(s); assessment of nontarget vegetation, soil types, climatic conditions, and important water resources. An evaluation of the benefits and limitations of each control method also needs to be accomplished [84].

Combinations of tillage plus cultural practices or herbicides applied regularly have controlled perennial sowthistle in agricultural settings [30]. No information is available on integrated control measures for perennial sowthistle in wildlands.

Timing of control measures may increase the effectiveness of integrated management techniques. Schimming and Messersmith [102] conducted artificial freezing experiments with perennial sowthistle. They determined a temperature of 1 oF (-17 oC) reduced survival of perennial sowthistle roots by 50% and a temperature of 4 oF (-15 oC) reduced total dry weight of emerging perennial sowthistle shoots by 50%. The authors speculate conditions that tend to minimize hardening, such as lack of photosynthetic material in fall after tillage or chemical treatment, stimulation of fall growth after tillage, or high nitrogen levels may increase injury caused by freezing temperatures in the field.

Physical/mechanical: Tillage generally reduces perennial sowthistle, but its effectiveness depends on plant growth characteristics at time of tillage [10,50,52], type of tillage being utilized [30,51], and frequency of tillage [92]. Intensive tillage is usually not appropriate in wildland settings, so it is not discussed further here.

Studies of mowing as a control method for perennial sowthistle show mixed results. Defoliation was less effective than burial for reducing infestations of perennial sowthistle in a study done in Sweden in 1967 [52], suggesting mowing is not as effective as tillage for control of perennial sowthistle [74]. However, Stevens [110] found defoliation an efficient method to control perennial sowthistle. Plants grown from root cuttings planted 3 May, had their leaves removed by hoe on 23 May when the largest leaves were about 6 inches (15 cm) long. The plants had the leaves removed again on 1 June, when leaves had again grown to about 6 inches (15 cm). After the 1 June defoliation, leaf growth was less vigorous. There was "very little" regrowth of leaves after a 1 July defoliation and none after a 19 July defoliation although weather conditions were favorable for growth. No plants appeared the next spring.

Fire: See the Fire Management Considerations section of this summary.

Biological: There appears to be limited biological agents available to help control perennial sowthistle. A tephritid fly from Europe that transforms the seedhead of perennial sowthistle into a gall has been released into Canada but has not become established [53]. Cystiphora sonchi, another fly native to Europe, was released into Canada and has become established in Alberta, Saskatchewan, Manitoba, and Nova Scotia [93]. Zollinger and Parker [133] report as many as 721 galls were formed on one plant of perennial sowthistle, but Lemna and Messersmith [74] state that no reduction in perennial sowthistle because of Cystiphora sonchi has been observed. A third fly, Liriomyza sonchi, has been authorized for release into Canada (Peschken and Derby 1988, reported in [74]).

Zollinger and Parker [133] provide a literature review of biological control efforts as of 1998.

Chemical: Auxin-type herbicides are the primary chemicals used to control perennial sowthistle. Perennial sowthistle is "moderately susceptible" to auxins such as 2,4-D, 2,4-DB, and MCPA in the seedling stage, and established stands are "moderately resistant" (Fryer and Makepeace, 1982, as reported in a literature review [74]). Growth of aerial portions can be retarded by auxin-type herbicides, and flowering can be completely suppressed if the plant is treated when growth is vigorous (Fryer and Makepeace 1982 as reported in a literature review [74]), and [77]. A more detailed discussion of chemical control of perennial sowthistle is provided by Lemna and Messersmith [74] and by Zollinger and Parker [133].

Cultural: Patches of perennial sowthistle were cut for hay or were pastured as an early control measure [111,129]. An alfalfa or alfalfa-grass mixture, regularly cut for hay, can eliminate 90% of perennial sowthistle in 3 years (Martin and others 1961 in [74]).

"Intensive" grazing by domestic sheep or cattle weakens perennial sowthistle when the animals eat new growth and sometimes roots [133]. Grazing also enhances other control practices. However, perennial sowthistle is classified as an "increaser" under heavy grazing because it increases as more palatable plants are preferentially grazed [70].


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Relevance to Humans and Ecosystems


Importance to Livestock and Wildlife

More info for the term: cover

Perennial sowthistle is "good" as a livestock feed [111,129]. Sheep and cattle will eat new growth and sometimes roots [133], and pronghorns were observed utilizing perennial sowthistle in central Montana during the fall [24].

Perennial sowthistle is considered "excellent" forage for rabbits [118] and Martin and others (as reported in [133], a literature review) state perennial sowthistle is a minor element in the diet of some North American birds.

Perennial sowthistle is listed as a nonnative plant occurring in critical habitat of the threatened desert tortoise in the Mojave and Colorado deserts. It is of concern because it competes with native plants vital to the tortoises' survival [17].

Palatability/nutritional value: Although perennial sowthistle compares favorably with alfalfa (Medicago sativa) for nutritional value, it is not especially palatable to grazing animals. Dry perennial sowthistle is about 10% protein by weight [19,20]. Palatability of perennial sowthistle to lambs was lower compared to grasses and alfalfa, and infestations of perennial sowthistle in pastures and hayfields may decrease overall forage feeding value [76].

Perennial sowthistle has equal or higher in vitro digestible dry matter, micro- and macromineral content and crude protein and lower neutral detergent fiber compared to alfalfa [76]:

Nutritional values for perennial sowthistle [76]
Sample date In vitro digestible dry matter concentration
(g kg-1)
Neutral detergent fiber concentration
(g kg-1)
Crude protein concentration
(g kg-1)
15 June 1981 818 312 164
29 June 1981 660 447 132
1 June 1982 792 267 214

Herbage macromineral and micromineral concentrations for perennial sowthistle are given in the following tables:

Herbage macromineral concentrations in g kg-1 [76]
Sample year Ca P K Mg
1981 (mean of 2 sample dates) 16.8 3.0 26.6 6.8
1982 (single sample date) 17.3 4.8 47.9 3.6

Herbage micromineral concentrations in µg g-1 [76]
Sample year Zn Cu B Mn Al Fe
1981 (mean of 2 sample dates) 22 10 26 63 393 334
1982 (single sample date) 40 10 26 53 83 108

Cover value: Cover value of perennial sowthistle for several classes of wildlife for 2 western states is provided by Dittberner and Olson [32] in the following table:

State Elk Mule deer White-tailed deer Pronghorn Upland game bird Waterfowl Small nongame bird Small mammal
Utah poor poor poor fair poor poor fair
North Dakota good good fair fair


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Other uses and values

Roasted roots of perennial sowthistle have been used like chicory (Cichorium intybus) root as an additive or a replacement for coffee. The young, tender leaves can be eaten raw in salads or cooked [118].

Most of the latex of perennial sowthistle is oil and may be a potential crop for oil or hydrocarbon production [19,20]. Perennial sowthistle is a good source of pentacyclic triterpenes, which may become important in the pharmaceutical industry [61].


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Sonchus arvensis

Sonchus arvensis (corn sow thistle, dindle, field sow thistle, gutweed, swine thistle, tree sow thistle, field sowthistle,[1] perennial sow-thistle[2] or field milk thistle [3]) is a medicinal plant. It is an invasive species in the Great Lakes region and was first sighted in 1865.[4]


  1. ^ Sonchus arvensis at USDA PLANTS Database
  2. ^ "BSBI List 2007" (xls). Botanical Society of Britain and Ireland. Archived from the original on 2015-02-25. Retrieved 2014-10-17. 
  3. ^ Sonchus arvensis at Plants For A Future
  4. ^ "List of invasive species in the Great Lakes Great Lakes United / Union Saint-Laurent Grands Lacs". Retrieved 2009-02-07. 
Creative Commons Attribution Share Alike 3.0 (CC BY-SA 3.0)

Source: Wikipedia


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Sonchus arvensis is introduced in temperate regions of all continents. Plants of the species prefer relatively cooler, moister climates and are more abundant in the northern part of North America.
Creative Commons Attribution Non Commercial Share Alike 3.0 (CC BY-NC-SA 3.0)

© Missouri Botanical Garden, 4344 Shaw Boulevard, St. Louis, MO, 63110 USA

Source: Missouri Botanical Garden


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Names and Taxonomy


The currently accepted scientific name for perennial sowthistle is Sonchus
arvensis L. (Asteraceae) [26,34,42,45,57,58,62,64,71,72,81,114,125,127]. There are
2 recognized subspecies:

S. arvensis ssp. arvensis

S. arvensis ssp. uliginosus (Bieb.) Nyman [45,72]

In this summary, perennial sowthistle will be used when discussing Sonchus
arvensis, and the subspecies will be referred to by their scientific names
when information pertaining to them individually is available.

Naturally occurring hybrids produced by the 2 subspecies have been detected in
areas where both subspecies occur [74].


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Common Names


perennial sowthistle

perennial sow thistle

field sowthistle


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For Sonchus arvensis spp. arvensis:

    Sonchus arvensis var. arvensis [26,42,64,125].

For Sonchus arvensis spp. uliginosus:

    Sonchus uliginosus [34,58,71,127]

    Sonchus arvensis var. glabrescens [26,42,64,114,125].


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