The Spurred Butterfly Pea, Centrosema virginium, is an herbaceous perennial with trailing and climbing vines 6 to 8 feet in length. Compound leaves composed of 3 leaflets are alternate on the vines. Leaf shape is narrow to elliptic 1 to 11/2 inch in length.
A member of the Fabaceae, Bean family, virginium, has a butterfly-like flower structure. The corolla consists of three pairs of petals. Two extra large petals are fused together to form a banner and two smaller petals are fused together in the shape of a boat keel. Two narrow petals are on either side of the keel and are called wings. The flower’s corolla is light lavender blue with white markings. Inflorescence is solitary.
Flowers are made up of 3 pairs of petals of unequal size. Result is that virginium is an asymmetrical flower. The flower is capable of division into symmetrical halves by only one longitudinal plane passing through the axes. This is called zygomorphic. For millions of years of co-evolution certain insects learned to approach virginium from only one direction to reach the nectar source. Insects coming in at angle will have no luck.
The specimen in the picture was found in a prairie alongside the Dog Track in Bonita Springs.
Photo by James Rodwell