papilionaceous

adjective

pa·​pil·​i·​o·​na·​ceous pə-ˌpi-lē-ə-ˈnā-shəs 

: having a corolla (as in the bean or pea) with usually five petals that include a large upper petal enclosing two lateral wings and a lower carina of two united petals

Word History

Etymology

Latin papilion-, papilio butterfly — more at pavilion

First Known Use

1668, in the meaning defined above