Bauhinia × blakeana

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Bauhinia × blakeana, commonly known as the Hong Kong orchid tree, is a hybrid legume in the Bauhinia genus. It is usually grown as a grafted plant and is best known for its large purplish‑red, orchid‑like flowers and thick, double‑lobed leaves.

Origin and appearance
The tree originated in Hong Kong around 1880. It was propagated from cuttings taken from a tree at a French mission near Pokfulam and later planted in the Hong Kong Botanical Gardens, where many cultivated trees today derive from that single original tree. Leaves are distinctive: two rounded lobes that form a heart- or butterfly‑shaped outline, about 7–10 cm long and 10–13 cm wide. The flowers are fragrant, about 10–15 cm across, and bloom from early November to the end of March.

Genetics and reproduction
B. × blakeana is sterile in most cases, meaning it does not readily produce seeds. It is a hybrid between Bauhinia purpurea and Bauhinia variegata. In 2025, a genome project showed that the maternal parent is B. purpurea and the paternal parent is B. variegata, supporting the idea that the hybrid originated from a rare single event rather than ongoing gene flow. Propagation is typically done by grafting, and the plant is often treated as a cultivar named Bauhinia 'Blakeana'. There have been a few instances of seed pods forming, but seeds have not generally germinated, indicating low fertility.

Symbol and culture
The Hong Kong orchid tree is a beloved symbol of Hong Kong. It has appeared on the city’s coat of arms, flag, and coins since 1997, and it is known locally as 洋紫荊 (yèuhng jīgīng). A statue of the plant stands in Golden Bauhinia Square. Its flowers are bright pinkish-purple in real life, but they are depicted as white on the flag. The tree is also used in other places as an emblem of the region and has been cultivated in nearby areas, including Taiwan.

Notes
Because all cultivated B. × blakeana trees come from the same original stock, researchers and horticulturists encourage renewed hybridization with the parental species to increase genetic diversity and reduce potential disease vulnerability.