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''Bauhinia'' × ''blakeana'' ( ross), commonly called the Hong Kong orchid tree, is a hybrid leguminous tree of the
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
''
Bauhinia ''Bauhinia'' () is a large genus of flowering plants in the subfamily Cercidoideae and tribe Bauhinieae, in the large flowering plant family Fabaceae, with a pantropical distribution. The genus was named after the Bauhin brothers Gaspard and ...
''. It has large thick leaves and striking purplish red flowers. The fragrant, orchid-like flowers are usually across, and bloom from early November to the end of March. Although now cultivated in many areas, it originated in
Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
in 1880 and apparently all of the cultivated trees derive from one cultivated at the Hong Kong Botanical Gardens and widely planted in Hong Kong starting in 1914. It is referred to as bauhinia in non-scientific literature though this is the name of the genus. It is sometimes called the Hong Kong orchid (). In Hong Kong, it is most commonly referred to by its Chinese name of ''(yèuhng jígīng)''. The ''Bauhinia'' double-lobed leaf is similar in shape to a heart or a butterfly, or a camel's footprint - hence the common name camel's foot. A typical leaf is long and wide, with a deep cleft dividing the apex. In Hong Kong the leaf is known as the "clever leaf" (), and is regarded as a symbol of wisdom. Some people use the leaves to make bookmarks in the hope that they will bring them good luck in their studies. It is sterile, which means it does not generally produce seeds or fruits, and is a hybrid between '' Bauhinia variegata'' and '' Bauhinia purpurea''. The 2008 research was able to identify the female parent as '' Bauhinia purpurea'', but it could not differentiate the male parent from ''Bauhinia variegata'' var. ''variegata'' or ''Bauhinia variegata'' var. ''candida''. This is not unexpected, as ''Bauhinia variegata'' var. ''candida'' is a white-flowered form of ''Bauhinia variegata'' var. ''variegata'', and not a separate species or sub-species. The 2005 research suggested ''Bauhinia'' × ''blakeana'' is genetically closer to '' Bauhinia variegata'', while the 2008 research indicated it is closer to '' Bauhinia purpurea'' instead. In 2025 the Bauhinia Genome Project definitively determined through a complete telomere-to-telomere reference assembly that ''Bauhinia purpurea'' is the maternal parent, and '' Bauhinia variegata'' the parental strain. Also supporting the hypothesis that ''Bauhinia × blakeana'' more likely originated from a rare single, recent hybridization event rather than recurrent gene flow. Propagation is by grafting. As it is only known in cultivation, it can also be named as a
cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...
: ''Bauhinia'' 'Blakeana'. Hong Kong orchid trees are usually sterile, yet here, too, there are exceptions. One tree has been found in Hong Kong that produces seeds, perhaps indicating that evolution or mutation has occurred, or that even though ''Bauhinia'' × ''blakeana'' is perhaps sterile when self-pollinated (the scientific study in 2005 established the low fertility of ''Bauhinia'' × ''blakeanas pollen when compared with its parental species ''Bauhinia purpurea'' or ''Bauhinia variegata''), however, it may perhaps be able to produce seeds when pollinated instead by its parental species ''Bauhinia purpurea'' or ''Bauhinia variegata'' or other related ''Bauhinia'' species. More scientific research will need to be carried out, e.g., artificial controlled cross-pollination experiments to confirm the ability of ''Bauhinia'' × ''blakeana'' in backcross or outcross to produce (fertile) seeds. Lawrence Ramsden of the University of Hong Kong's Department of Botany is conducting the search to find out if there are any more individuals that can produce seeds – if so, they could benefit propagation of the tree for horticulture. Two previous instances of seeds found from ''Bauhinia'' × ''blakeana'' specimens failed to germinate. Development of seed pods (but no seeds) from ''B.'' × ''blakeana'' have been observed on three trees in Tai Po and Kowloon in Hong Kong. These three ''B.'' × ''blakeana'' trees with numerous seed pods were grown alongside ''B. purpurea'', ''B. variegata'' (white flowered form) and ''B. variegata''. At the time (March in Hong Kong), both ''B. blakeana'' and ''B. purpurea'' were flowering, therefore, the pollens for development of ''B. blakeana'' seed pods may have been contributed from ''B. purpurea''.


History

This tree was discovered in around 1880 by a French Catholic Missionary of the Paris Foreign Missions (MEP), near the ruins of a house above the shore-line of western
Hong Kong island Hong Kong Island () is an island in the southern part of Hong Kong. The island, known originally and on road signs simply as "Hong Kong", had a population of 1,289,500 and a population density of , . It is the second largest island in Hong Kon ...
near
Pok Fu Lam Pok Fu Lam ( zh, t=薄扶林, links=no, labels=no) or Pokfulam is a residential area on Hong Kong Island, at the western end of the Southern District. It is a valley between Victoria Peak and Mount Kellett, around Telegraph Bay. Pok Fu L ...
and propagated to the formal botanical gardens in Victoria/Central. The first thorough scientific description of the tree was made by
Stephen Troyte Dunn Stephen Troyte Dunn (26 August 1868, Bristol - 18 April, 1938, Sheen, Surrey, England) was a British botanist. He described and systematized a significant number of plants around the world, his input most noticeable in the Taxonomy (biology), ta ...
, Superintendent of the Botanical and Forestry Department, who assigned it to the genus ''Bauhinia'' in his paper of 1908. Dunn named the tree for "Sir Henry and Lady Blake", the former being
Sir Henry Blake Sir Henry Arthur Blake ( zh, c=卜力, sl=Buk1 Lik6; 8January 184023February 1918) was an Irish-born British colonial administrator who held the governorships of six British colonies over the course of his career. Early life, family and caree ...
, British Governor of Hong Kong, from 1898 to 1903. Sir Henry and Lady Blake were thus thanked for their promotion of the Hong Kong Botanic Gardens. Dunn's description was based on the trees in the Hong Kong Botanical Gardens, which had been grown from cuttings taken from trees cultivated in the French Mission at Pokfulam, on the west coast of Hong Kong Island, which in turn were derived from a tree (or trees) found nearby. As far as is known, all the French Mission cuttings were taken from a single tree, so all Hong Kong orchid trees today would be clones of the original tree. Dr Lawrence Ramsden of the University of Hong Kong’s Department of Botany estimates that this clonal origin would mean that ''B.'' × ''blakeana'' could be susceptible to decimation by epidemics, though it has so far avoided major diseases. In order to avoid the susceptibility of ''B.'' × ''blakeana'' to diseases due to the lack of genetic diversity from the current clones of a single ''B.'' × ''blakeana'' tree back in 1880s, efforts should be made to re-hybridise the parental species of ''B.'' × ''blakeana'', ie, crossing '' B. purpurea'' and '' B. variegata'' to generate new hybrid specimens of ''B.'' × ''blakeana'' instead to add new genetic materials to the current stock of ''B.'' × ''blakeana''. To solve the mystery of Hong Kong Bauhinia's parentage a community crowdfunded Bauhinia Genome project was launched in 2015, finally completing the genome and determing the maternal and parenal species in 2025.


Usage as an emblem

Since 1997 the flower appears on Hong Kong's coat of arms, its flag and its coins; its Chinese name has also been frequently shortened as 紫荊/紫荆 (洋 ''yáng'' means 'foreign' in Chinese, and this would be deemed inappropriate by the PRC government), although 紫荊/紫荆 refers to another genus called ''
Cercis ''Cercis'' is a genus of about 10 species in the subfamily Cercidoideae of the pea family (biology), family Fabaceae. It contains small deciduous trees or large shrubs commonly known as redbuds in the USA. They are characterised by simple, rou ...
''. A
statue A statue is a free-standing sculpture in which the realistic, full-length figures of persons or animals are carved or Casting (metalworking), cast in a durable material such as wood, metal or stone. Typical statues are life-sized or close to ...
of the plant has been erected in
Golden Bauhinia Square The Golden Bauhinia Square () is an open area in Wan Chai, Hong Kong. The square was named after the giant statue of a golden '' Bauhinia blakeana'' at the centre of the area, situated outside the Hong Kong Convention and Exhibition Centre, wher ...
in Hong Kong. Although the flowers are bright pinkish purple in colour, they are depicted in white on the Flag of Hong Kong.
Hong Kong Airlines Hong Kong Airlines Limited (HKA), operating as Hong Kong Airlines (), is an airline based in Hong Kong, with its headquarters in the Tung Chung district and its main hub at Hong Kong International Airport. It was established in 2006 as a m ...
uses BAUHINIA as its
callsign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally assi ...
. The
endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
plant of
Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...
was introduced to
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
in 1967. In 1984 it was chosen to be the city flower of
Chiayi City Chiayi (,), officially known as Chiayi City, is a Provincial city (Taiwan), city located in Chianan Plain in Regions of Taiwan, southwestern Taiwan, surrounded by Chiayi County with a population of 263,188 inhabitants as of January 2023. The H ...
, in southwestern
Taiwan Taiwan, officially the Republic of China (ROC), is a country in East Asia. The main geography of Taiwan, island of Taiwan, also known as ''Formosa'', lies between the East China Sea, East and South China Seas in the northwestern Pacific Ocea ...
.


Gallery

File:Tree I IMG 2075.jpg, Tree in
Kolkata Kolkata, also known as Calcutta ( its official name until 2001), is the capital and largest city of the Indian state of West Bengal. It lies on the eastern bank of the Hooghly River, west of the border with Bangladesh. It is the primary ...
,
West Bengal West Bengal (; Bengali language, Bengali: , , abbr. WB) is a States and union territories of India, state in the East India, eastern portion of India. It is situated along the Bay of Bengal, along with a population of over 91 million inhabi ...
,
India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...
. File:Flowers I IMG 2101.jpg, Flowers in Kolkata File:Leaf I MG 2069.jpg, Leaf in Kolkata File:Flower buds I IMG 2064.jpg, Flower buds in Kolkata File:Bark I IMG 2073.jpg, Bark in Kolkata File:Bauhinia × blakeana.jpg, flower in Ajmiriganj,
Sylhet Sylhet (; ) is a Metropolis, metropolitan city in the north eastern region of Bangladesh. It serves as the administrative center for both the Sylhet District and the Sylhet Division. The city is situated on the banks of the Surma River and, as o ...
,
Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...


References


External links


National Flower of Hong Kong
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{{DEFAULTSORT:Bauhinia blakeana blakeana Culture of Hong Kong Regional symbols of Hong Kong Garden plants of Asia Ornamental trees Hybrid plants Fabales of Asia Taxa named by Stephen Troyte Dunn