Loading profile. Please wait . . .
Amorpha nitens Boynt.
Shining Indigo-bush
Federal Protection: No US federal protection
State Protection: No Georgia state protection
Global Rank: G4
State Rank: S1?
Element Locations Tracked in Biotics: Yes
SWAP High Priority Species (SGCN): Yes
Element Occurrences (EOs) in Georgia: 24
Habitat Summary for element in Georgia: Rocky, wooded slopes; alluvial woods
Perennial, deciduous shrub with erect or sprawling, branching, hairless stems 3 - 10 feet (1 - 3 meters) tall; the branches are also hairless, sometimes with a few inconspicuous glands. The leaves are compound, 4 - 7 inches (10 - 22 cm) long, alternate, with 7 - 19 leaflets, and are conspicuously black when dried. The leaflets are mostly 0.8 - 2.8 inches (2 - 7 cm) long and 0.4 - 1.7 inch (1 - 4.5 cm) wide; oblong, elliptic, or oval; shiny above, sparsely hairy beneath, rounded at the tip with the midrib only slightly or not at all exserted; the margins of the leaflets are not inrolled. The inflorescences are erect, spike-like racemes 2 - 10 inches (5 - 25 cm) tall, with smooth or hairy stalks. Flowers consist of a smooth, reddish-green, 5-lobed, non-glandular calyx (2.5 - 4 mm long) with white-fringed edges; a single purple-black petal; and 10 long, purple, orange-tipped stamens extending beyond the petal. Fruits are hairless, glandless, oblong, one-seeded pods about 0.25 inch (0.5-0.8 cm) long.
Indigo-bush (Amorpha fruticosa) is a common shrub, 3 - 12 feet (1 - 4 m) tall, occurring statewide on riverbanks and marsh shores, and in forests, woodlands, and disturbed sites. Its leaves and stems are slightly to very hairy. Its leaves are not shiny and do not turn black when dried. They have 9 - 23 leaflets, and the midvein of the leaflet extends into a pointed or swollen tip. Its calyxes are covered with small, bulging glands, and the flower is purple.
Dwarf Indigo-bush (Amorpha herbacea var. herbacea) has conspicuously hairy stems, leaves, calyxes, and (usually) fruits. Its leaves are not shiny, and they have 21 - 45 leaflets with inrolled margins and round, glandular knobs at the tips. Its flowers are white or purple.
Appalachian Indigo-bush (Amorpha glabra) occurs in dry ridgeline and slope forests in the Blue Ridge, upper eastern Piedmont, and Coastal Plain in Georgia. It is 3 - 6 feet tall, with hairless stems and leaves. Its leaves are not shiny and have 9 - 19 leaflets, often bearing a slightly enlarged, gland-like tip; the margins are not inrolled. Its flowers are purple.
Georgia Indigo Bush (Amorpha georgiana) occurs in pine flatwoods and on sandy stream terraces in the Coastal Plain. It is less than 3 feet (1 m) tall, and its stems and leaves are hairless or nearly so. Its leaves have 13 - 39 leaflets, each tipped with a tiny, sharp point that is sometimes capped with a round gland. Its flowers are purple or blue, and its fruits are not hairy. For more information, see: https://www.georgiabiodiversity.org/natels/profile?es_id=16161
Florida Lead-bush (Amorpha herbacea var. floridana) occurs on sandy stream terraces and in pine flatwoods in the Coastal Plain. It is 1.3 - 5 feet (0.4 - 1.5 meters) tall and has mostly hairless stems, leaves, and fruits. Its leaves have 21-45 leaflets tipped with a tiny, round, glandular knob; the leaflet margins are rolled under. Its flowers are purple, and the fruits are hairless. For more information, see: https://www.georgiabiodiversity.org/natels/profile?es_id=15495
Schwerin's Indigo-bush (Amorpha schwerinii) occurs in rocky upland woods in the Piedmont. It is 3 - 13 feet (1 - 4 meters) tall and has hairy stems, leaves, and calyxes. Its leaves have 9 - 29 leaflets with the midvein extending beyond the tip into a round gland; the leaflet margins are not inrolled or only slightly so. Its flowers are purple, and the fruits are hairy. For more information, see: https://www.georgiabiodiversity.org/natels/profile?es_id=15978
Rocky glades and ridgelines (shale, limestone, sandstone, etc.), riparian forests, limestone-based forests, and rich, wooded slopes.
There is little published information about the life history of Shining Indigo-bush. Common Indigo-bush (Amorpha fruticosa), a close relative, is pollinated by bees seeking both pollen and nectar from the flowers, including Andrena quintilis, a specialist pollinator of Amorpha species. The caterpillars of Gray Hairstreak, Silver-spotted Skipper, and Southern Dogface butterflies, as well as those of Black-spotted Prominent moths, use Common Indigo-bush leaves as food; it is possible they also use other species of Amorpha as host plants. As with most species in the legume family (Fabaceae), nitrogen-fixing bacteria live in nodules on the roots of all Amorpha species. Zasada and Martineau (2008) describe the collection, storage, and planting of seeds from Amorpha species.
Shining Indigo-bush flowers April–June and fruits June–August. Since it is distinguished from similar species largely on the basis of leaf and stem traits, it may be identified throughout the growing season.
GA west to Louisiana (where possibly extirpated) and Oklahoma, north to Illinois and Kentucky. It is rare throughout most of its range. In Georgia, Shining Indigo-bush (Amorpha nitens) occurs in 11 counties throughout Georgia (except for Blue Ridge counties), half of those in the Ridge & Valley and Cumberland Plateau ecoregions.
Logging, stream impoundment, conversion of habitat to agriculture or residential/commercial development, invasion by exotic pest plants, cattle grazing, and deer browsing.
Shining Indigo-bush is ranked S1? by the Georgia Department of Natural Resources, indicating that it may be critically imperiled but that information is lacking on which to base a definite rank. It has been documented at 22 sites in Georgia since the 1930s, 13 of these since 2013. Ten of these populations occur on state or private conservation lands.
Protect sites from impoundment and habitat conversion. Monitor sites for over-browsing by deer and for invasion by exotic pest plants. On state-owned lands, avoid placing roads and recreational facilities near populations.
GADNR. 2019. Element occurrence records for Amorpha nitens. Georgia Department of Natural Resources, Wildlife Resources Division. Social Circle, Georgia.
Hilty, J. 2019. Species account for Amorpha fruticosa. Illinois Wildflowers. Accessed 3 July 2019. https://www.illinoiswildflowers.info/trees/plants/false_indigo.htm
Isley, D. 1990. Leguminosae (Fabaceae), volume 3, part 2, Vascular flora of the southeastern United States. University of North Carolina Press, Chapel Hill.
NatureServe. 2019. Species account for Amorpha nitens. NatureServe Explorer: an online encyclopedia of life, Version 7.1. NatureServe, Arlington, Virginia. Accessed 8 June 2019. http://explorer.natureserve.org/servlet/NatureServe?searchName=Amorpha+nitens
Weakley, A.S. 2015. Flora of the southern and mid-Atlantic States. University of North Carolina Herbarium, University of North Carolina, Chapel Hill.
Wilbur, R.L. 1975. A revision of the North American genus Amorpha (Leguminosae-Psoraleae). Rhodora 77(811): 337-409. https://www.jstor.org/stable/23311397?seq=1#metadata_info_tab_contents
Zasada, J.C. and D. Martineau. 2008. Amorpha L. – amorpha, indigobush. In, F.T. Bonner and R.P. Karrfalt, eds. “Woody Plant Seed Manual,” pages 250-254. U.S. Department of Agriculture, Forest Service, Agriculture Handbook 727. Accessed 5 July 2019. https://www.fs.usda.gov/nsl/Wpsm%202008/A%20genera.pdf
Linda G. Chafin
Linda G. Chafin, 3 July 2019: original account
