Plant of the Week
Butterfly Pea (Clitoria mariana L.)
By Christopher David Benda
Butterfly pea is a stunning wildflower in the Pea family (Fabaceae). The genus name “Clitoria” comes from the Greek word “kleitoris,” which refers to the shape of the flower resembling female genitalia, and “mariana” possibly refers to a woman Linnaeus was courting when he named this plant. It is called butterfly pea because it is a plant in the pea family, but surprisingly, it is not frequented by butterflies. Rather, the expanded banner looks like a butterfly.
This is a large wildflower with one to three showy purple flowers that are up to two inches long. It has the characteristic banner, wing, and keel floral structure of flowers in the Pea family, but the banner is much expanded, concave, and lined with dark lavender markings. Later in the season, the plant may produce cleistogamous flowers, meaning flowers that self-fertilize and therefore never fully form. This is a well-known trait of many families, including the Pea family. Fruits are flattened legumes with two valves that twist upon dehiscence.
Butterfly pea is a perennial vine up to three feet long, but it is a twining vine and not a climbing vine so look for this one growing along the ground. Like many plants in the Pea family it has trifoliate leaves. These compound leaves are alternate, stalked, and have three leaflets over an inch long, with the terminal leaflet on a long stalk. The leaflets are broadest at the base and taper to a pointed tip. The leaves also have stipules, which are wings of leafy tissue at the base of the leaf. The entire plant is hairless.
Butterfly pea occurs in dry and rocky woods. It is an uncommon plant in the southeastern United States. Of the 35 species of Clitoria worldwide, this is the only widespread species native to North America.