Clethra alnifolia L.
Wet pine flatwoods (WPF-T), wet pine savannas (SPS-T, SPS-RF, WLPS, VWLPS).
Frequent. Jun–Jul ; Sep–Oct . Thornhill 585, 613, 670, 715 (NCSC). Specimens seen in the vicinity: Sandy Run [Hancock]: Taggart SARU 258 (WNC!); Sandy Run [Neck]: Wilbur 53648, 53702 (DUKE!). [= Clethra alnifolia L. var. alnifolia sensu RAB; = FNA, Weakley]
General: White Alder Family (Clethraceae). Coastal sweet pepperbush is a large deciduous shrub that grows to 2.5 m tall. The bark is smooth, reddish-orange or gray in color, and 2 to 3 mm in diameter. Twigs are reddish-orange covered with dense white hairs. Leaves are alternate, simple, 5 to 8 cm long, and toothed toward their tips. They are medium to dark green, turn golden yellow in the fall and have appressed white hairs along the midvein. Flowers are up to 1 mm long and 0.8 mm wide, composed of 5 white fused petals. Seventeen to one hundred fragrant flowers form the bottlebrush-like inflorescences that are about 10 cm long and 2 cm wide. The fruiting stalk has many miniature oval 3-seeded capsules that are winter-persistent and are good identification features. Coastal sweet pepperbush produces leaves in late spring, flowers in July and August, and sets fruit in September and October. The yellow fall foliage persists for two to four weeks.
Distribution: This is the only species in the genus Clethra that is native to North America. It occurs from southern Maine and New Hampshire, south to eastern Texas and Florida. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site (http://plants.usda.gov).
Habitat: Coastal sweet pepperbush is found in wet woods, thickets, marshes, swales and bogs, along lake and stream edges, and near rocks in water. It is typically not a dominant species in plant communities. Common overstory associates include cypress, Atlantic white cedar, coastal pine species, red maple, magnolias, and beech.
Clethra, Clethra alnifolia var. tomentosa, Clethra angustifolia, Clethra bracteata, Clethra incana, Clethra michauxii, Clethra paniculata, Clethra pubescens, Clethra pumila, Clethra scabra, Clethra tomentosa, poorman’s soap, summer sweet, sweet pepper bush, white alder.
southern Maine, southern New Hampshire, Massachusetts, southeastern New
York, and eastern Pennsylvania [13,27].
Occurrence in North America
MA MS NH NJ NY NC OH PA RI SC
TN TX VA VT WV
The USDA hardiness zones for coastal sweet pepperbush are 4 to 9. It grows naturally in poorly drained, moist soils and will get larger and produce more suckers if provided plenty of water. Once established, it can also thrive on drier, well-drained soils. The optimum soil pH is approximately 4.5. Coastal sweet pepperbush is moderately salt tolerant and can be grown near, but not directly behind, beaches.
Coastal sweet pepperbush is a shade-tolerant understory shrub that grows under the canopy of old-growth trees. It will grow in full sun, but does best in a light, dappled shade.
Regularity: Regularly occurring
Regularity: Regularly occurring
Regularity: Regularly occurring
Coastal sweetpepperbush is a native, large, deciduous shrub that grows up to 8
feet (2.5 m) tall . It has woody twigs and stoloniferous roots. The
bark is reddish-brown. The fruit is a capsule divided into three
Catalog Number: US 903690
Collection: Smithsonian Institution, National Museum of Natural History, Department of Botany
Verification Degree: Unknown verification or is "ined."
Preparation: Pressed specimen
Collector(s): N. Catalan
Year Collected: 1914
Locality: Mt. Makiling., Luzon, Laguna, Philippines, Asia-Tropical
Elevation (m): 950 to 950
- Type: Blanco, F. M. 1845. Fl. Filip. 259.
Sweet peperbush grows in humid, tropical to temperate climates . It
is found on moderate to poorly drained sites, in acid swamps or in sandy
soils [1,14,27]. Common overstory associates include cypress (Taxodium
spp.), Atlantic white-cedar (Chamaecyparis thyoides), loblolly pine
(Pinus elliottii), slash pine (P. taeda), pitch pine (P. rigida),
eastern white pine (P. strobus), pond pine (P. serotina), spruce pine
(P. glabra), red maple (Acer rubrum), magnolia (Magnolia spp.), and
beech (Fagus grandifolia). Common understory associates include
laurelleaf greenbrier (Smilax laurifolia), switchcane (Arundinaria
tecta), inkberry (Ilex glabra), large gallberry (I. coriacea), zenobia
(Zenobia pulverulenta), swamp cyrilla (Cyrilla racemiflora), southern
bayberry (Myrica cerifera), and saw-palmetto (Serenoa repens) [3,15,17].
Key Plant Community Associations
Coastal sweetpepperbush is very seldom a dominant species in plant communities.
It is listed as a dominant shrub in only one area in the Coastal Plain
of Virginia .
Habitat: Cover Types
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: hardwood, swamp
1 Jack pine
5 Balsam fir
12 Black spruce
13 Black spruce - tamarack
14 Northern pin oak
15 Red pine
20 White pine - northern red oak - 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
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
64 Sassafras - persimmon
65 Pin oak sweetgum
69 Sand pine
70 Largeleaf 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 oak
89 Live oak
91 Swamp chestnut oak - cherrybark oak
92 Sweetgum - willow oak
96 Overcup oak - water hickory
97 Atlantic white cedar
98 Pond pine
101 Baldcypress - tupelo
103 Water tupelo - swamp tupelo
104 Sweetbay - swamp tupelo - redbay
108 Red maple
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
More info for the term: bog
K090 Live oak - sea oats
K091 Cypress savanna
K093 Great Lakes spruce - fir forest
K094 Conifer bog
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K099 Maple - basswood forest
K100 Oak - hickory forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K108 Northern hardwoods - spruce forest
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
K115 Sand pine - scrub
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
FRES18 Maple - beech - birch
Fire Management Considerations
controlled with regular prescribed burning .
Plant Response to Fire
Coastal sweetpepperbush will probably sprout after fire. Severe fire or
regular prescribed burning greatly reduces coastal sweetpepperbush and other
common associate shrubs [2,25]. In National Forest lands in South
Carolina, coastal sweetpepperbush gradually increased in areas that had not
been burned for 3 years .
Immediate Effect of Fire
Most fires probably top-kill coastal sweetpepperbush. Its stolons may be
killed by fires severe enough to consume the organic soil.
off-site colonizer; seed carried by animals or water; postfire yr 1&2
surviving stolons .
More info for the terms: shrub, shrubs
Coastal sweetpepperbush is a shade-tolerant understory shrub. It is a mid to
late seral species. It grows under the canopy of old-growth trees
[6,21]. Coastal sweetpepperbush either does not become a dominant shrub or
does not dominate for very long. Other shrubs such as switchcane
(Arundinaria tecta) dominate, with coastal sweetpepperbush reduced to a
Sexual: The flower of coastal sweetpepperbush is insect pollinated; the fruit
is probably distributed by animals .
Growth Form (according to Raunkiær Life-form classification)
More info for the terms: geophyte, phanerophyte
Undisturbed State: Phanerophyte (nanophanerophyte)
Undisturbed State: Phanerophyte (microphanerophyte)
Burned or Clipped State: Cryptophyte (geophyte)
Life History and Behavior
Molecular Biology and Genetics
Barcode data: Clethra alnifolia
Statistics of barcoding coverage: Clethra alnifolia
Public Records: 2
Specimens with Barcodes: 2
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: NNR - Unranked
NatureServe Conservation Status
Rounded Global Status Rank: GNR - Not Yet Ranked
National NatureServe Conservation Status
Rounded National Status Rank: N1 - Critically Imperiled
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Coastal sweet pepperbush is listed as a special concern species in Maine and as threatened in Tennessee. Please consult the PLANTS Web site (http://plants.usda.gov) and your State Department of Natural Resources for this plant’s current status (e.g. threatened or endangered species, state noxious status, and wetland indicator values).
Pests and potential problems
Damage caused by spider mites can be severe on plants in hot, dry locations.
Cultivars, improved and selected materials (and area of origin)
The USDA NRCS Plant Materials Program has not released any cultivars of coastal sweet pepperbush for conservation use.
Several ornamental cultivars are available through commercial nurseries. These cultivars include ‘Anne Bidwell,’ ‘Creels Calico,’ ‘Hummingbird,’ ‘Paniculata,’ ‘Pink Spires,’ ‘Ruby Spice,’ ‘September Beauty,’ and ‘Summersweet Clethra.’ These cultivars have been developed for flower size and color, foliage variegation and shine, plant stature, and extended bloom time.
Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government.” The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”
Coastal sweet pepperbush can be propagated by seeds, summer cuttings, or sucker division. Seeds are cold stratified for 30 days and germinated under spring temperatures.
Collect 10 cm long softwood cuttings at the end of May or the beginning of June and strip the leaves from the lower two-thirds of the cutting. Wound the lower portion of the stem and apply a powder or liquid root hormone compound. Place cuttings in coarse sand that is 7 to 10 cm deep and lightly water at least every 2 hours. The medium can be any well-drained mixture that does not contain soil. Provide shade to the cuttings for the first 7 to 10 days to allow the cuttings to harden off before exposing them to full sun. For best rooting results, place cuttings in an intermittent misting system.
Legginess occurs with age among coastal sweet pepperbush plants. Aggressive root suckering also occurs with age, which is an asset if naturalization or moderate erosion control is desired.
Coastal sweet pepperbush can build up and create a fire hazard. It can be controlled with regular prescribed burning. Most fires probably top-kill sweet pepperbush, but the plant can resprout from surviving stolons. Fires severe enough to consume the organic soil may kill stolons.
Relevance to Humans and Ecosystems
Other uses and values
Coastal sweetpepperbush is sometimes used to arrest succession of tall trees
along pathways. It has been planted after herbicide application along
electrical transmission , telephone, railroad, roadside, and pipeline
right of ways, where low-growth woody vegetation does not interfere with
general operation .
Coastal sweetpepperbush has often been planted as an ornamental because of its
attractive and fragrant white flowers .
Importance to Livestock and Wildlife
It is eaten by deer and cattle when other forage is limited .
Erosion control: Coastal sweet pepperbush spreads by sending up new shoots, forming a thicket of low bushes. Growth from root suckering will provide moderate erosion control along streams and ponds.
Garden and landscape: The foliage and flowers of coastal sweet pepperbush make it an attractive garden shrub. It can be used in a mixed shrub hedge or border and pruned to maintain a small size. The lush green leaves turn to golden yellow in autumn. The fragrant flowers last up to 6 weeks or more during the middle of summer while other flowering shrubs are not blooming due to the heat.
Utility right of ways: Coastal sweet pepperbush is sometimes used to halt succession of tall trees along pathways. It has been planted following herbicide
application along electrical transmission, telephone, railroad, roadside, and pipeline right of ways. Its low
stature does not interfere with the general operations around these utility areas.
Wildlife: The fragrant white flowers and nectar of coastal sweet pepperbush attract hummingbirds and butterflies. Deer eat it only when other forage vegetation is limited. Birds eat the fruit and aid in seed dispersal.
Clethra alnifolia (coastal sweetpepperbush or summersweet), is a species of flowering plant in the genus Clethra of the family Clethraceae, native to eastern North America from southern Nova Scotia and Maine south to northern Florida, and west to eastern Texas.
It is a deciduous shrub growing to 1.5–3 m (4 ft 11 in–9 ft 10 in) tall. The leaves are obovate to oblong, 4-10 cm long and 2-4 cm broad, with a serrated margin; they are green turning yellow-golden during the autumn. The flowers are white or very pale pink, 5-10 mm in diameter, and have a sweet, somewhat cloying fragrance, the flowers attractive to bumblebees; they are produced in racemes up to 15 cm long and 2 cm broad in late summer, depending on the cultivar. The "pepper" part of the common name derives from the mature fruits, capsules which have a vague resemblance to peppercorns, however, with no element of spiciness.
Sweetpepperbush is typically used as a shrub for natural gardens, or is placed alongside a stream or pond in order to delay erosion. Limiting its landscaping use is the fact that it does not leaf out until very late in the season. Several cultivars have been selected for garden use, including 'Ruby Spice', with strongly pink flowers; 'Hummingbird', for its dwarf size; and 'September Beauty'.
Names and Taxonomy
Comments: Flora of North America (vol. 8, 2009) accepts Clethra alnifolia and C. tomentosa as distinct species, C. alnifolia occurring from Nova Scotia to Florida, C. tomentosa occurring only in southerns states, from South Carolina to Florida, west to Louisianna. Kartesz (1999) included C. tomentosa in synonomy of C. alnifolia.
Comments: Flora of North America (vol. 8, 2009) accepts Clethra alnifolia and C. tomentosa as distinct species, C. alnifolia occurring from Nova Scotia to Florida, C. tomentosa occurring only in southern states, from South Carolina to Florida, west to Louisianna. Kartesz (1999) included C. tomentosa in synonomy of C. alnifolia.
sweet pepper bush
poor man's soap
alnifolia L. The Clethra genus is in the family Clethraceae and
consists of two species. There are two recognized varieties of coastal
Clethra alnifolia var alnifolia L.
Clethra alnifolia var tomentosa (Lam.) Michaux
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