This genus includes many and varied species of perennials, vines, and shrubs, but all have the distinctive flowers and foliage of the pea family. Of the two listed here, one is a popular twining vine, the other a native wildflower.
C. mariana. BUTTERFLY PEA, ATLANTIC PIGEON WINGS. Zones US, MS, LS, CS, TS; USDA 6-11. Native to the dry woods, sand hills, and scrub of the eastern U.S. (from New Jersey to Florida), west to Texas and Mexico. Upright and spreading, sometimes twining, thin-stemmed plant that may reach 3 ft. tall. Leaves with three ovate leaflets to 2 in. long; lavender flowers to 2 in. long, 112 in. wide in early summer. Dies to ground in winter. Best with moderate to regular water and full sun but tolerates some drought and light shade. Good for naturalized areas.
C. ternatea. BLUE PEA VINE. Perennial in Zones TS; USDA 10-11; annual elsewhere. Native to tropical Americas and Asia. A fast-growing, twining vine to 10 ft.; often used to decorate trellises and posts. Blooms continuously in warm weather, bearing deep blue, white-eyed flowers to 2 in. long and 1 in. wide. Leaves consist of five to nine leaflets, each up to 2 in. long. Plant in well-drained soil; give full sun and regular water. Easy to start from seed (soak seed for 3 to 4 hours before sowing). Can bloom as soon as 6 weeks after sowing.