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Sorbus americana Marsh.
American Mountain-ash
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G5
State Rank: S1
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): No
Element Occurrences (EOs) in Georgia: 5
Habitat Summary for element in Georgia: Grassy balds; northern hardwood forests
Shrub or small tree up to 30 feet (10 meters) tall, usually shorter, with a short trunk and bronze to gray bark; winter buds are green to purple, shiny, 0.27 - 0.8 inch (0.7 - 2 cm) long. Twigs are stout, reddish-brown, with crescent shaped leaf scars. The leaves are 6 - 10 inches (15 - 25 cm) long, alternate, with leaf stalks up to 3 inches long. Each leaf has 9 - 17 opposite, toothed, lance-shaped leaflets 1.6 - 4 inches (4 - 10 cm) long, hairless, with toothed margins, dark green upper surfaces, and whitish lower surfaces; turning bright orange-red in the fall. The flower clusters are 2.4 - 6 inches (6 - 15 cm) across, flat-topped, held at the tips of branches with 125+ flowers. Flowers are about 0.26 inch (5 - 8.5 mm) wide, with 5 tiny, white petals and many stamens. Fruits in large clusters at the tips of the branches, each fruit about 0.2 inch (4 - 7 mm) across, round, shiny, bright red to orange-red, lasting well into winter.
Black Chokeberry (Aronia melanocarpa) has small, flat-topped clusters of 5 - 20 white flowers; its leaves are simple and its fruits are black.
The white, flat-topped flower clusters and compound leaves resemble Elderberry (Sambucus canadensis), a wetland shrub with soft, pithy stems and opposite leaves.
Staghorn Sumac (Rhus typhina, Special Concern) has alternate leaves with opposite leaflets; its stems and fruits are very hairy, and its elongated, greenish-white flower cluster is found only at the top of the main stem. It occurs on rock outcrops and in open mountain forests in 5 north Georgia counties.
None in Georgia.
Moist areas on rocky mountain tops, grassy balds, and openings in high-elevation hardwood forests.
Mountain Ash reproduces sexually by seed and also by stump sprouting after disturbance. Its flowers are pollinated by a variety of insects. In areas where it is abundant, its fruits, which are high in antioxidants phenolic compounds, are an important food for birds and other wildlife which disperse the seeds. Deer are known to eat its leaves, twigs, and bark. Mountain Ash is susceptible to bacterial fireblight which shrivels its leaves at the ends of branches.
Surveys are best conducted during flowering (June–July) but leaves and growth form are distinctive throughout the growing season, the bright orange-red leaves are showy in the fall, and the fruits often last through the winter.
Georgia, north to Newfoundland and west to Minnesota and Saskatchewan.
Logging, clearing, and home-building on mountain summits and ridgelines.
Sorbus americana is ranked S1 by the Georgia Department of Natural Resources, indicating that the species is critically imperiled in Georgia. Five populations are known, most in the Chattahoochee National Forest.
Avoid logging or other mechanical clearing on high-elevation ridges and mountain summits.
Becerra-Herrera, M, M.R. Lazzoi, A. Sayago, R. Beltran, R. Del Sole, and G. Vaspallo. 2015. Extraction and Determination of Phenolic Compounds in the Berries of Sorbus americana Marsh and Lonicera oblongifolia (Goldie) Hook. Food Analytical Methods 8: 2554-2559. https://link.springer.com/article/10.1007/s12161-015-0151-5
Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.
Foote, L.E. and S.B. Jones, Jr. 1989. Native shrubs and woody vines of the southeast. Timber Press, Portland, Oregon.
Kirkman, L.K., C.L. Brown, and D.J. Leopold. 2007. Native trees of the southeast. Timber Press, Portland, Oregon.
Lance, R. 2004. Woody plants of the southeastern United States: a winter guide. University of Georgia Press, Athens.
NatureServe. 2020. Sorbus americana species account. NatureServe Explorer. NatureServe, Arlington, Virginia. https://explorer.natureserve.org/Taxon/ELEMENT_GLOBAL.2.158784/Sorbus_americana
Peattie, D.C. 1966. Natural history of trees of eastern and central North America, 2nd edition. Bonanza Books, New York.
Radford, A.E., H.E. Ahles, and C.R. Bell. 1968. Manual of the vascular flora of the Carolinas. University of North Carolina Press, Chapel Hill.
Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill. http://www.herbarium.unc.edu/flora.htm
Zika, P.F. and S.M. Bailleul. 2015. Sorbus americana species account. Flora of North America, Vol. 9. http://beta.floranorthamerica.org/Sorbus_americana
Linda G. Chafin
L. Chafin, Aug. 2008: original account.
K. Owers, Feb. 2010: added pictures.
L. Chafin, May 2020: updated original account.
