Ouachita Lead Plant
(Amorpha ouachitensis)
Left: Amorpha ouachitensis in ASMSA Garden in Late Summer 2023.
Above: Amorpha ouachitensis blooming in early summer.
Plant Characteristics
Plant Preference/Growing Conditions:
Prefers full sun to partial shade and average, medium moisture, well drained soil. Also can grow in poor, sandy, somewhat dry soils. Can spread by self-seeding. Tolerates all pHs.
Growth Habit/Description:
Perrinial, medium-sized deciduous shrub, 3-6’ in height, 3-6' in width, has slender, dense 4"-8" spiky dense clusters of purple flowers, alternate pinnate ooblong leaves, 10 leaflets in a bunch.
Bloom Season:
Purple, lavender flowers with yellow anthers bloom from late April to early June.
Fall and/or Winter Interest?
Yes; Since it is deciduous, its leaves turn a light yellow during the fall.
Distribution
Habitat:
Ouachita Lead Plant can often be found in clearings of rocky creeks and banks of streams, rocky ridges, glades, and dry rocky sandstone slopes. Its habitat is threatened by clear cutting, alterations to stream banks and the conversion of wetlands. It occupies similar habitats to other plants such as Calamovilfa arcuata, Streptanthus squamiformis, and Gaura demareei.
Native to Arkansas? Yes
Native to Garland County? Yes, but considered rare
Endemic to Arkansas? Yes, endemic to the Ouachitas of western Arkansas and eastern Oklahoma.
Ecological Value
Host Plant for Caterpillars?
Similar to Amorpha fruitcosa, Ouachita Lead Plant is a host plant for the California & southern dogfaces, Silver-spotted Skipper (Epargyreus clarus), Gray hairstreak, and Hoary edge skipper.
Other Known Ecological Value?
Butterflies, bees, and pollinators are attracted to the plant. Since Ouachita Lead Plant is a legume, it is a nitrogen fixer. Like other Amorpha plants, it is considered a 'medium' nitrogen fixer.
Other Interesting Facts
Origin of Name:
Amorpha is derived from the Greek word amorphos, meaning shapeless or deformed in reference to the corolla of this pea family genus lacking wings and a keel (parts of the flower).
Lookalike:
Ouachita Lead Plant is also referred to as Ouachita False Indigo, due to its similarities to the genus Indigofera. The Indigofera tinctoria looks the most similar, however it has more of a red/pink tone, and appears rarely in other southern states.
Related Species:
Amorpha ouachitensis looks very similar and can be mistaken for its close relatives, Amorpha fruticosa (Bastard Indigo). Both grow in the same areas, however, the leaflets of Bastard Indigo are slightly smaller than Ouachita Lead Plant, as well as the Bastard Indigo leaflets turning black upon drying unlike Ouachita Lead Plant.
References
Ladybird Johnson Wildflower Center Plant Database. Austin (TX): University of Texas--Austin. Amorpha ouachitensis. [Cited 2023, Sept 8]. Available from: https://www.wildflower.org/plants/result.php?id_plant=AMOU
USDA Plants. Complied by Bogler, David. Ouachita False Indigo Physical Description. [Cited 2023, Sept 8] Available from: https://eol.org/pages/418066/articles
Missouri Botanical Garden. St. Louic (MO). Amorpha ouachitensis. [Cited 2023, Sept 8] Available from: https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?taxonid=280284
McCue, Kimberlie. Center for Plant Conservation. c 2010. Amorpha ouachitensis. [Cited 2023, Sept 8] Available from: https://web.archive.org/web/20111026044848/http://www.centerforplantconservation.org/Collection/CPC_ViewProfile.asp?CPCNum=108#Distribution
Oklahoma Natural Heritage Inventory. Norman (OK). Amorpha ouachitensis, Ouachita Indigobush. [Cited 2023, Sept 8] Available from: https://web.archive.org/web/20120809212121/http://www.oknaturalheritage.ou.edu/amorpha2.htm
United States Department of Agriculture. Natural Resources Conservation Service. Amorpha fruticosa L. [Cited 2023, Sept 8] Available from: https://plants.usda.gov/home/plantProfile?symbol=AMFR
North Carolina Extension Gardener Plant Toolbox. Raleigh (NC): North Carolina State University. Amorpha fruticosa (Bastard Indigo). [Cited 2023, Sept 8] Available from: https://plants.ces.ncsu.edu/plants/amorpha-fruticosa/
Last Edited by Kira Burnett, September 2023.