By Isla Grundy
Family: Fabaceae – Caesalpinioideae (Purple Bauhinia, Orchid or Butterfly Tree).
This is a plant of tropical and subtropical climates. It is native to East and South-East Asia. It usually grows where the rainfall is between 800 and 5000mm, at altitudes of between 500 and 3000m and where the mean annual temperature is between 12 and 21 degrees. The growth rate is relatively good at lower altitudes but slows down above 1600m. It demands plenty of light and requires good drainage. Once established the species is frost-hardy but is the least drought-hardy compared to other species of Bauhinia. It is widely planted as an ornamental tree in parks and along avenues for its showy fragrant, purple flowers. However, the weak wood of the branches is susceptible to breakage in storms and it has been found to be weedy in wetter areas such as Hawaii.
The generic name commemorates two Swiss botanists, the Bauhin brothers Jean (1541-1613) and Gaspard (1560-1624). The double lobes of the leaf exemplify the two brothers. The specific name refers to the purple colour of the flowers. There are about 300 species of the genus Bauhinia found in tropical regions.
Bauhinia purpurea is a small to medium-sized deciduous fast-growing shrub or tree with a round, symmetrical, moderately dense crown to 10m tall and young branches that become glabrous (i.e. hairless) or nearly so – glabrescent. The bark is pale grey brown, fairly smooth to slightly fissured and scaly. The heartwood is brown, hard and durable. In its natural habitat the tree is deciduous, flowering from September to November when the plant is leafless. The tree starts flowering at an early age of 2-3 years. The leaves are simple and alternate, with a rounded to shallow-cordate base and deeply 2-lobed at the apex. The winter flowers are numerous, purple to nearly white or at least purple- marked, velvety around 3-4 cm long. The flowers are followed by long, slender, brown, flat seed pods.
Uses: The young leaves and flowers of various Bauhinia species are eaten in Asia as a side dish with rice, or used to flavour meat and fish. The leaves make good animal fodder and are greedily eaten by sheep, goats and cattle, with a protein content estimated at 12.6%. In an experiment in Nepal, B.purpurea was found to increase milk production by lactating buffaloes.
The bark of Bauhinia is used to make rope and contains considerable amounts of tannin. The medicinal uses of the bark can be largely attributed to the presence of these tannins – poulticing to reduce swelling and bruises and to ripen ulcerations and boils. In India, the bark is extensively used for glandular diseases and as a poison antidote, while the leaves are administered as a cough medicine. The flowers are said to be laxative and are used in curries and pickles, while the tree yields an edible gum. The wood is used both as a fuel and for agricultural implements. Bauhinia purpurea, with its deep root system and high root: shoot ratio, is a suitable species for slope stabilisation. The tree coppices well and can stand heavy lopping.
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