Phanera purpurea Seeds | Purple Orchid Tree
LATIN NAME: Phanera purpurea
COMMON NAME: Purple Orchid Tree, Purple Bauhinia, Camel’s Foot
Plant Profile
The purple orchid tree is a small tree of six to ten metres with a smooth grey trunk, two-lobed leaves shaped like a camel’s foot and loose clusters of five-petalled flowers in pink and purple. The flowers appear in autumn, from September into November, when most trees are past their best.
It grows from India through Myanmar and is planted across the tropics as a street tree. The Hong Kong emblem tree, Bauhinia blakeana, is a sterile hybrid between this species and the white-flowered orchid tree, and it is propagated only from cuttings, which is why every specimen in the territory is a clone. The bark is smooth and grey, and the tree casts a light shade that allows grass to grow beneath it, which is one reason it is planted along streets.
Science & Biotechnology
The hybrid origin was confirmed by DNA work in the 2000s: Bauhinia blakeana is a cross between Phanera purpurea and Phanera variegata, found in Hong Kong in the 1880s and never found in the wild. It is self-sterile, sets no seed, and every tree in the territory descends from cuttings of that one plant.
The species differ in their stamens, which is the practical way to tell them apart: this one carries three or four fertile stamens, the white orchid tree carries five, and the sterile hybrid carries five or seven with no viable pollen. The leaf is the same camel’s foot in all three, which is why the trees are so often confused.
Uses & Benefits
The tree is planted as a street tree and in parks for its autumn flower, and it is one of the few trees that flowers in the dry season in southern China. The young leaves and flowers are eaten as a vegetable in India, and the bark is used for tanning and for cordage.
The bark and the root are used in Ayurvedic medicine as an astringent, and the gum from the trunk is used as a substitute for tragacanth. The wood is hard and dark and is used for agricultural implements, though the tree is rarely cut for timber. The flowers are also used to make a yellow dye in India, and the young pods are cooked as a vegetable in some districts.
Growing from Seed
Soak the seed for a day, since the coat is hard, and sow at two centimetres in a warm, free-draining mix. Germination takes one to three weeks, and the seedlings grow fast, reaching a metre in the first season.
Plant out in full sun in any soil that drains, and water through the first two dry seasons. The tree tolerates drought and poor soil but not frost, and it is damaged at minus two. Prune after flowering, since the tree flowers on the previous season’s wood and a hard winter cut removes the coming display.
Our Take
An autumn-flowering street tree, and the parent of the sterile hybrid that stands on the Hong Kong flag. Plant it for the flowers in September.
Related Reading
More species in the same orbit as Purple Orchid Tree: