Hawaii wild bean

Vigna owahuensis is an annual or perennial herb growing up to 40 cm (16 in) long. Each leaf has three hairy leaflets of widely varying shape and size. Flowers occur singly or in clusters of up to four. They are light yellow or greenish in color and are about 2 or 2.5 cm (0.79 or 0.98 in) long. The fruit is a long, thin legume pod up to 9 cm (3.5 in) in length. The pod may be slightly inflated or not. It contains up to 15 gray or black beans around .5 cm (0.20 in) long.

It is endemic to Hawaii, where it is known from seven small populations on the islands of Hawaii, Molokai, Lanai, and Kahoolawe. Though it was described from a specimen collected on Oahu it is now extirpated from that island. It was also known from Niihau, Maui, and Kauai in the past. This plant grows in many types of shrubland and grassland habitat, as well as in some cultivated areas. It occurs on cinder cones and offshore islets and exposed coral reefs.