Webster's Revised Unabridged Dictionary · 1913

Papilionaceous

Papilionaceous , adjective

1.
Resembling the butterfly.
2.
(a) (Botany) Having a winged corolla somewhat resembling a butterfly, as in the blossoms of the bean and pea.
(b)
(Botany) Belonging to that suborder of leguminous plants (Papilionacea) which includes the bean, pea, vetch, clover, and locust.