Shrubs with leaves divided featherwise into many leaflets. Spikelike, 3- to 6-in.-long clusters of blue or purple, single-petaled flowers typically bloom in early summer. In cold weather, plants may die back nearly to the ground; in warmer areas, they should be cut back severely to prevent lankiness. Tough and undemanding, withstanding heat and wind. Butterflies love the flowers.
A. canescens. LEAD PLANT. Native to the High Plains from Canada to Texas. About 3 ft. tall and wide, with silvery, downy foliage.
A. fruticosa. INDIGO BUSH, FALSE INDIGO. Native to eastern U.S. Lanky grower reaches 1015 ft. tall and wide, with light green foliage. Needs hard pruning in winter or early spring to maintain some degree of compactness.
A. texana (A. roemeriana). INDIGO BUSH. Native to the Texas Hill Country. Grows to 39 ft. high and 35 ft. wide, with silvery, downy leaves and spring bloom. This shrub is quite drought tolerant, requiring little supplemental water.