Description
Raceme Milkvetch is a coarse, herbaceous perennial with few to many erect stems, 15-70 cm high, and arising from a woody taproot and branched rootcrown. The pinnately compound leaves are 4-15 cm long with 11-31 narrowly to broadly elliptic leaflets. Foliage is thinly to densely covered with short hairs. Inflorescences with 15-70 densely clustered flowers arise from the axils of the upper leaves. The nodding, whitish flowers are 16-21 mm long with a partially reflexed upper petal and purplish tinged lower petals. The calyx is 8-11 mm long and glabrous or with scattered hairs. The pendant, oblong-elliptic pods have a basal, 3-7 mm long stalk, are glabrous, triangular in cross-section, with 3 sides that are nearly flat and equal-width, and 15-30 mm long.
Diagnostic Characteristics
The combination of coarse, erect stems, short pubescence, and pendant pods, triangular in cross-section, is diagnostic of this species in the n. Great Plains. The more common A. DRUMMONDII is similar but has pods dorsiventrally compressed with 2 parallel grooves on the bottom, and has foliage with long spreading hairs.
Habitat
This taxon grows in calcareous and gypsic or seleniferous saline clay and silty soils, on bluffs, knolls, plains, halophytic grasslands, alluvial bottoms and roadsides on clay, shale, or gypsum (Castillon 2023, FNA 2023).