There are some 200 species of Bauhinia, the genus of showy flowering trees and shrubs commonly known as orchid tree and named for the 16th-and-17th-century Swiss botanist brothers Bauhin. Perhaps the species best known in Southern California are Purple orchid tree (B. purpurea, B. variegata) and Hong Kong orchid tree (B. X blakeana).
From winter into spring, Purple orchid tree is cloaked with fragrant blossoms whose petals, in shades of pink and purple, are arranged to give the appearance of orchids.
Hong Kong orchid tree flowers from late autumn to spring with orchid-like blooms in pink and purple tones, frequently in the same blossom, and is generally regarded as the most beautiful of all the Bauhinias.
Other Bauhinia species bloom in shades of pink, purple, red, white and yellow. Orchid tree is native to southeastern China, Vietnam, Sri Lanka and northern India.
Purple orchid tree is well adapted to most of Southern California (Sunset zones 18-24, 13), but Hong Kong orchid tree needs the mild winter climates associated with the immediate coast, Southern California thermal belts and low desert (Sunset zones 24, 19, 21, 23, 13). Preferred cultural conditions call for well-drained acidic soil – orchid tree is subject to chlorosis – and full sun, with some tolerance for very light shade; Purple orchid tree grows rapidly to about 35 feet and nearly as wide.
Its natural inclination is to develop multiple trunks, but it can readily be trained when young to grow from a single trunk. The branches droop as the tree develops, requiring pruning under the canopy to allow pedestrian and vehicular clearance and to prevent the tree from morphing into an oversized bush.
Hong Kong orchid tree is also a fast grower, but smaller, reaching 20 feet high and wide. Both species are deciduous, though the Hong Kong orchid tree sheds just part of its foliage, and then for only a brief period. Twin-lobed leaves shaped somewhat like hearts are common to Bauhinias. (In some areas, local natives regard these leaves as symbols of cleverness.)
Bauhinias are in the pea family and, following bloom, Purple orchid tree produces a large number of woody bean pods that are quite a mess to clean up. Hong Kong orchid tree, on the other hand, is a sterile hybrid and does not produce pods.
Bauhinias are ideally suited to tropical and subtropical landscapes, where they can be used as shade trees, focal specimens or street trees. Remember, however, the messy pods and necessary under-canopy pruning when situating a tree. Another factor to bear in mind is orchid tree’s brittle branches that tend to break easily in high winds.
Borers, caterpillars and mites can occasionally be problem pests for orchid tree. It is also subject to leaf spot and leaf scorch disease, but generally the damage is limited to small trees not yet well established.
Orchid tree has been classified as a Category I invasive species by Florida’s Exotic Pest Plant Council, meaning it is considered capable of altering Florida’s native plant communities by displacing native species and the like. It is not, however, listed as an invasive plant by the California Invasive Plant Council.
