Amorpha is a genus of plants in the pea family, Fabaceae. All the species are native to North America, from southern Canada, most of the United States (US), and northern Mexico. They are commonly known as false indigo. The name Amorpha means "deformed" or "without form" in Greek and was given because flowers of this genus only have one petal, unlike the usual "pea-shaped" flowers of the Faboideae subfamily. Amorpha is missing the wing and keel petals.
The desert false indigo or indigo bush (Amorpha fruticosa), is a shrub that grows from 3 m to 5 m tall. The species is considered a rare species in the US state of West Virginia and in the Canadian provinces of Manitoba and Ontario, but is considered an invasive plant in some areas of the northeastern and northwestern United States and in southeastern Canada, beyond its native range, and has also been introduced into Europe.
The lead plant (Amorpha canescens), a bushy shrub, is an important North American prairie legume. Lead plant is often associated with little bluestem (Schizachyrium scoparium), a common prairie grass. Native Americans used the dried leaves of lead plant for pipe smoking and tea.
Amorpha species are used as food plants by the larvae of some Lepidoptera species including Schinia lucens, which feeds exclusively on the genus.
Amorphol, a rotenoid bioside, can be isolated from plants of the genus Amorpha.