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Amorpha georgiana Wilbur
Georgia Indigo Bush
Federal Protection: No US federal protection
State Protection: Endangered
Global Rank: G3
State Rank: S1
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 6
Habitat Summary for element in Georgia: Longleaf pine flatwoods; stream terraces
Woody subshrub 1 - 3 feet (30 - 100 cm) tall with smooth or nearly hairless stems. The leaves are compound, alternate, and up to 7 inches (18 cm) long, alternate, with 11 - 47 leaflets; the leaf stalks are up to 0.8 inch (2 cm) long. The leaflets are 0.2 - 0.5 inch (0.6 - 1.2 cm) long, oblong, with inrolled margins; midvein of each leaflet extends beyond the tip into a tiny, sharp point. Flowers are in spike-like clusters 1 - 2.8 inches (2.5 - 7 cm) long, and have only 1 dark purple petal and 10 orange-tipped stamens. Fruit pods are legumes less than 0.2 inch (0.5 cm) long, wider at the tip, tapering to the base.
Indigo-bush (Amorpha fruticosa) is a common shrub, 3 - 12 feet (1 - 4 m) tall; its leaflets are 0.4 - 1.6 inch (1 - 4 cm) long, and its leaf stalks are 0.4 - 1.6 inches (1 - 4 cm) long. The midvein of the leaflet extends into a pointed or swollen tip, and the margins of the leaflets are not inrolled.
Goat’s-rue (Tephrosia virginiana) is a common perennial herb with similar compound leaves that have 15 - 25 leaflets. The leaflets lack the sharply pointed tip, and its stems are hairy. It has typical, 5-petaled pea-family flowers with an erect, yellow banner petal; two pink wing petals; and a pink keel.
Three other similar Indigo-bushes are rare in Georgia, see below.
Florida Indigo-bush (Amorpha herbacea var. floridana) is a low shrub found on the Alapaha River floodplain. For more information, see: https://georgiabiodiversity.org/natels/profile?es_id=15495
Shining Indigo-bush (A. nitens), a tall shrub found on rocky slopes and floodplains in several northwest, Piedmont, and Coastal Plain counties. For more information, see: https://georgiabiodiversity.org/natels/profile?es_id=19342
Schwerin’s Indigo-bush (A. schwerinii), a tall shrub, occurs in rocky, upland woods in several Piedmont counties. For more information, see: https://georgiabiodiversity.org/natels/profile?es_id=15978
Longleaf Pine woodlands, flatwoods, and savannas; sunny openings around Altamaha Grit and flint kaolin outcrops; stream terraces.
Georgia Indigo-bush flowers are probably pollinated by the same insects as are Amorpha fruticosa and Amorpha canescens: short- and long-tongued bees, flower bees, and wasps seeking nectar and pollen. Pearl crescent butterflies also visit the flowers. The leaves are high in protein and heavily browsed by mammals, including deer. Plants flower and fruit the first and second years after a fire.
Surveys are best conducted during flowering (mid-April–early May) although fruits, which may persist until early April of the following year, are helpful in identification. Plants flower and fruit the first and second years after a fire.
Georgia, North Carolina, and South Carolina, in the Coastal Plain.
Fire suppression, conversion of habitat to pine plantations, agriculture, and development.
Amorpha georgiana is listed as Endangered by the State of Georgia and is ranked S1 by the Georgia Department of Natural Resources, indicating that it is critically imperiled in the state. Three populations have been observed in Georgia, none on conservation lands. Only one is likely to be extant.
Apply prescribed fire in Longleaf Pine stands every 2-3 years. Avoid clearcutting and other mechanical disturbances to the understory. Georgia's single extant population is genetically distinctive and "deserves special conservation consideration because it has numerous private alleles, is geographically isolated, and has historical value as the type locality for the species. Focused effort on conservation of this population is needed because its habitat has been severely degraded through mechanical site preparation for tree farming and the overgrowth of brush due to prolonged fire suppression" (Straub and Doyle 2007).
Chafin, L.G. 2007. Field guide to the rare plants of Georgia. State Botanical Garden of Georgia and University of Georgia Press, Athens.
GADNR. 2019. Element occurrence records for Amorpha georgiana. Georgia Department of Natural Resources, Wildlife Resources Division. Social Circle, Georgia.
Miller, V.M. 2004. Habitat characterization of Amorpha georgiana var. georgiana groups at Fort Bragg, North Carolina. M.S. thesis, North Carolina State University, Raleigh. https://repository.lib.ncsu.edu/handle/1840.16/2506
NatureServe. 2019. Amorpha georgiana var. georgiana comprehensive report. NatureServe Explorer. Arlington, Virginia. http://explorer.natureserve.org/servlet/NatureServe?searchName=Amorpha%20georgiana
Nelson, G. 2006. Atlantic Coastal Plain wildflowers. Globe Pequot Press, Guilford, Connecticut.
Norden, H. and K. Kirkman. 2006. Field guide to common legume species of the longleaf pine ecosystem. Joseph W. Jones Ecological Research Center, Newton, Georgia. https://tinyurl.com/ya6vy9kj
Sorrie, B.A. 1993. Amorpha georgiana var. georgiana element stewardship abstract. The Nature Conservancy. Arlington, Virginia.
Sorrie, B.A. 1995. Amorpha georgiana var. georgiana status survey. North Carolina Natural Heritage Program, Division of Parks and Recreation, Raleigh.
Straub,S.C.K. and J.J. Doyle. 2007. Conservation genetics of Amorpha georgiana (Fabaceae), an endangered legume of the southeastern United States. Molecular Ecology 18: 4349-4365. https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-294X.2009.04353.x
Wilbur, R.L. 1954. An undescribed dwarf species of Amorpha from Georgia. Rhodora 56(672): 261-265. https://www.jstor.org/stable/23306632?seq=1#metadata_info_tab_contents
Wilbur, R.L. 1964. A revision of the dwarf species of Amorpha (Leguminosae). Journal of the Elisha Mitchell Scientific Society 80(2): 52-65.
Wilbur, R.L. 1963. The leguminous plants of North Carolina. North Carolina Agricultural Experiment Station, Raleigh. https://www.jstor.org/stable/24334854?seq=1#metadata_info_tab_contents
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
Linda G. Chafin
L. Chafin, Sept. 2007: original account.
K. Owers, Jan. 2010: updated status and ranks, added pictures.
Z. Abouhamdan, April 2016: updated link.
L. Chafin, Jan 2020: updated original account.
