Native to eastern and midwestern U.S. The false indigos somewhat resemble lupines (Lupinus), but they have deep taproots that enable them to survive difficult conditions. They are long-lived plants that become large clumps with many stems and bloom spikes. They resent transplanting once established. Bluish green leaves are divided into three leaflets. Flower spikes to 1 ft. long top the plants in late spring or early summer. Flowers resemble small sweet peas and are followed by inflated seedpods; both flowers and pods are interesting in arrangements. Remove spent flowers to encourage repeat bloom. Not usually damaged by deer.
B. alba. WHITE FALSE INDIGO. To 3 ft. tall and wide; clusters of white flowers. Attractive, smoky gray stems. 'Wayne's World' is vigorous and full, to 4 ft. tall and loaded with 18-in.-long flower spikes.
B. australis. BLUE FALSE INDIGO. Grows 36 ft. tall, 4 ft. wide; flowers are indigo blue. Several complex hybrids offer improvements on the basic species. 'Blueberry Sundae' is compact and refined at 3 ft. tall and wide, with lavender-blue flowers. 'Cherries Jubilee' is about the same size but sports deep maroon buds that open into bicolored flowers of maroon and yellow. 'Dutch Chocolate', to 2 ft. tall and 3 ft. wide, has black-purple buds that mature to rich brown. 'Lemon Meringue', 3 ft. tall and wide, produces lemon-yellow blooms. B. a. minor is about half the size of the species and comes into bloom earlier.
B. bracteata leucophaea (B. leucophaea). PLAINS WILD INDIGO. To 11 ft. high, 22 ft. wide. Creamy white to pale yellow flowers are held nearly horizontally on arching stems. Especially attractive where it can be viewed from belowplanted on a hillside or spilling over a wall, for example.
B. 'Carolina Moonlight'. Hybrid between B. alba and B. sphaerocarpa. To 44 ft. high, 34 ft. wide. Profuse clusters of soft yellow flowers. Foliage turns silvery blue in summer heat.
B. 'Purple Smoke'. Hybrid between B. australis and B. alba, reaches 4 ft. tall and has violet flowers with dark purple centers.
B. sphaerocarpa. YELLOW WILD INDIGO. To 23 ft. tall and wide, with clear yellow blossoms.