About Orbexilum onobrychis (Nutt.) Rydb.
Orbexilum onobrychis, commonly known as French-grass or lanceleaf scurfpea, is a species of flowering plant in the legume family, Fabaceae. It is native to the eastern United States, with its natural range concentrated in the Midwest and Upper South. Its primary natural habitats are prairies and riverbanks, and it typically grows in mesic or wet areas. It is an uncommon species, and can be found in both high-quality prairie remnants and more disturbed areas. This plant is a rhizomatous perennial that forms large colonies. It produces pinnately trifoliate leaves with large lanceolate leaflets. Its pale blue or purple flowers grow in racemes, and bloom from late spring to early summer. Its fruits are 6–8 mm long beans that have a distinctively warty texture. The caterpillars of the rare moth Hystrichophora loricana are known to exclusively use Orbexilum onobrychis as a foodplant.
