Members of the forget-me-not family, these are shrubs or trees of tropical or subtropical origin with showy flowers and rough-surfaced, almost sandpapery leaves. Species grown in the U.S. include Southwestern and tropical natives. The two listed here do best in the lower Rio Grande Valley and along the Texas coast from Corpus Christi to Brownsville.
C. boissieri. TEXAS OLIVE, ANACAHUITA. Native to New Mexico, Texas, Mexico. Grayish green, oval leaves to 3 in. long; clusters of white, 2-in.-wide flowers with yellow throats. Begins flowering in midspring and continues over a long season; may bloom again in autumn. Naturally reaches 810 ft. high and 68 ft. wide, but can be pruned low (35 ft.); can also be trained as small tree. Regular moisture until established; thereafter, give little to moderate water.
C. sebestena. GEIGER TREE. Native to the West Indies. Usually 1015 ft. (possibly 25 ft.) tall and wide, with dark green leaves 912 in. long and half as wide. Brilliant orange-red summer flowers, to 2 in. wide, come in large clusters. Regular water.