A small genus of North American deciduous shrubs with imparipinnate leaves and small purple or white flowers disposed in dense terminal racemose panicles. Only one petal, the upper, is developed in this genus, the others are wanting, hence the generic name.

1. A. fruticosa. Bastard Indigo. - This is the only species at all common in gardens. It is a shrub about 6 to 9 feet high, with elegant pinnate leaves and purple flowers. There is a narrow-leaved and a small-leaved variety, and one with bluish flowers.