The "Single-Tree Origin" of the Bauhinia — Hong Kong's Emblematic Flower Was Born in Pok Fu Lam, on the Same Hillside as HKU

Wild-history section · Module 15 · Deep-dive, botany chapter. This piece is a documented campus geography / ecology investigation (not legend), reported on the facts, marked credibility "Corroborated by multiple sources." The named individual (the Governor after whom the tree is named) is a historical figure named in a positive context, recorded per the naming convention. For a campus ecology overview see ../05-campus/museums-and-ecology.md; for campus geography see ../05-campus/campus-geography.md; for the University Hall (originally the French mission's Nazareth House) connected to this piece, see ../05-campus/buildings-landmarks.md.

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# I. Discovery: Pok Fu Lam, 1880

• According to the Wikipedia entry on the Bauhinia^※, the tree was reportedly first discovered around 1880 near an abandoned building in Pok Fu Lam, by a French missionary.
• According to the same entry^※, the missionary is said to have subsequently propagated the tree on the grounds of the nearby Béthanie sanatorium, run by the Missions Étrangères de Paris; it was from there that the tree was later introduced to the Hong Kong Botanic Gardens.

Where exactly the "abandoned building" stood is somewhat more clearly indicated in official sources. According to official research by the Hong Kong Herbarium under the Agriculture, Fisheries and Conservation Department^※, the species was first formally mentioned in the Botanical and Forestry Department's 1903 annual report, which stated that the tree had reportedly been discovered "twenty to thirty years earlier" — i.e., roughly in the 1870s–1880s — in woodland on Mount Davis, and that the mission "found it among the ruins of a house near the seashore." Cuttings were said to have then been taken to the Béthanie garden for cultivation, and later introduced to the Botanic Gardens. Mount Davis sits directly adjacent to Pok Fu Lam, on the same western Hong Kong Island hillside as HKU's campus — which means that the long-vague "abandoned building" is, per this official annual-report account, more specifically the ruins of a house near the seashore around Mount Davis, rather than a generic "somewhere in Pok Fu Lam." The same official page also records^※ that in 1908, Stephen Troyte Dunn, then Superintendent of the Botanical and Forestry Department, completed a Latin scientific description and formally published the tree as a new species in a botanical journal — meaning roughly thirty years passed between the "chance find in the wild in the 1870s/80s" and its "formal naming in 1908," a full chain running from a wild specimen, through domestication by mission gardeners, to confirmation and naming by the colonial botanical bureaucracy. In this original description, Dunn recorded a specific note of thanks; as quoted on the official page^※: "The preservation of this Bauhinia is due to the fathers of the Missions Étrangères de Paris at Pokfulam." — likely the earliest official "acknowledgment" concerning this tree, crediting that unnamed group of missionary gardeners directly.

According to the Wikipedia entry on Béthanie^※, this "Pok Fu Lam sanatorium" was in fact Béthanie — built by the Missions Étrangères de Paris between 1873 and 1875 for the rest and recuperation of missionaries serving in the Far East. Over the nearly one hundred years from its completion in 1875 to its closure in 1974, it reportedly received more than 6,000 missionaries from various places. The same source states that the garden below the sanatorium's hillside was tended by a number of priests with an interest in horticulture, who introduced seeds and plants from various places, including — reportedly — some of the earliest cultivated Bauhinia specimens in Hong Kong. The Béthanie missionary gardeners were, in that sense, the first link in the artificial-propagation chain of this "single-tree" city flower.

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# II. The mystery of the "single tree": a sterile hybrid

The most unusual thing about the Bauhinia is that it cannot reproduce by seed.

• According to a 2005 study in American Journal of Botany on its hybrid origin^※, the Bauhinia is a hybrid of two related species, B. purpurea and B. variegata, and is entirely sterile.
• According to that study and Wikipedia^※, precisely because it is sterile, essentially all Bauhinia trees existing today are very likely vegetative-propagation (cutting/grafting) descendants of that single original tree — genetically, they are close to being clones of one and the same tree.

Context. A city's floral emblem that cannot fruit, and is kept alive only by successive generations of artificial "copying" — this makes the Bauhinia an uncommon case in botany of a "single-individual origin." In a sense, every Bauhinia across Hong Kong is a "copy" of that one tree from Pok Fu Lam in 1880.

Horticultural researchers have also studied this "vegetative propagation" process in detail. According to a study on vegetative propagation of the Bauhinia published in the Brazilian journal SciELO^※, because the tree is entirely sterile and cannot produce viable seed, propagation depends solely on asexual techniques such as cuttings, air layering, and grafting; the study further found that semi-lignified cuttings taken in spring (without requiring growth hormone) or summer cuttings (treated with a certain concentration of indole-3-butyric acid, IBA) show higher survival rates, while cuttings taken in autumn or winter show very low survival and rooting rates and hold little practical propagation value; grafting, meanwhile, showed generally low — sometimes negligible — success rates regardless of rootstock species, grafting method, or rootstock age. This suggests that, historically, the widespread cultivation of the Bauhinia in Hong Kong has depended heavily on cutting-based propagation under specific seasonal and technical conditions — every Bauhinia now blooming on a Hong Kong street is, behind the scenes, the product of a set of horticultural procedures requiring precise timing and technique, rather than a matter of "simply take a cutting and it grows."

The question of "why it is sterile" only received a direct molecular-level answer in recent years. According to a haplotype-resolved, telomere-to-telomere (T2T) whole-genome study published in GigaScience in April 2025^※, the research team constructed chromosome-level genome assemblies for both B. purpurea and B. variegata, and from these assembled a haplotype-resolved genome for the Bauhinia; chloroplast genome comparison indicated that B. purpurea is the maternal parent of the Bauhinia — reportedly the first confirmation, based on genomic evidence rather than morphological observation alone, of which species served as mother and which as father in this cross-species pairing that occurred on the Pok Fu Lam hillside. The study also indicated that the Bauhinia's sterility likely stems from irregular chromosome segregation and abnormal spindle formation during meiosis in its diploid genome, preventing it from producing functional pollen and ovules — in other words, the fact that this "hybrid oddity" of 1880 bears no fruit was, per this account, not a chance horticultural occurrence but something written into its chromosomal structure. The study's sampling site was Shenzhen, not Hong Kong itself, but the Bauhinia specimens analysed reportedly belong to the same clonal lineage as the original Hong Kong tree, so the conclusion can be regarded as molecular-level corroboration of the Pok Fu Lam "single-tree" origin account.

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# III. Naming and "elevation" to a symbol of Hong Kong

• According to the Wikipedia entry^※, the tree was named B. blakeana after Sir Henry Blake, Governor of Hong Kong from 1898 to 1903; its first detailed scientific description was published by Stephen Troyte Dunn of the Botanical and Forestry Department in 1908.
• According to CGTN's account^※ and Wikipedia, the Bauhinia was selected, in 1965, as Hong Kong's city/regional flower; from 1997, its white blossom form has appeared as the central design on Hong Kong's regional flag and emblem.

Being "selected as city flower" was not a decision made overnight, but followed a formal municipal process. According to the Wikipedia entry on Hong Kong's city flower, as compiled^※, in 1964 the Urban Council's Urban Amenities and Recreation Committee first nominated five candidate flowers — besides the Bauhinia (also called "Hong Kong Bauhinia"), these included Sterculia lanceolata, Illicium henryi, Enkianthus quinqueflorus, and Bauhinia purpurea; after discussion, Urban Council members selected among them, and on 19 January 1965 the Hong Kong government formally announced acceptance of the Urban Council's proposal, officially designating the Bauhinia as Hong Kong's city flower. This means that today's ubiquitous Bauhinia was, at the time, "chosen" from among five candidates rather than being the sole option — its selection was reportedly linked to its long flowering season, strong ornamental appeal, and the fact that it was first discovered within Hong Kong, giving it a certain "native" character.

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# IV. A century of naming confusion: "Zijing hua" and the Bauhinia

Hong Kong's city flower also carries a naming dispute that persists to this day: what many people call "紫荆花" (zijing hua, "redbud flower") is, in fact, not the Hong Kong city flower Bauhinia at all, but an entirely different plant.

• According to the Wikipedia entry on Hong Kong's city flower, as compiled^※, when the Chinese-language draft of the Basic Law of the Hong Kong Special Administrative Region of the People's Republic of China was being drawn up from the 1980s, the Chinese text used the name "紫荆花" rather than the more precise official name "洋紫荆" (Bauhinia). This usage was carried through into Article 10 of the Chinese text of the Basic Law adopted in April 1990.
• This simplification in wording has produced a botanical mix-up that persists today: 紫荆 (Cercis chinensis) belongs to genus Cercis in the pea family, a deciduous shrub common in northern China that flowers with small pink-purple blooms before its leaves appear each spring; whereas Hong Kong's city flower, the Bauhinia (Bauhinia × blakeana), belongs to genus Bauhinia in the pea family, an evergreen tree with large, palm-sized blossoms — while the two are distant relatives within the same pea-family subfamily, they differ substantially in appearance, flowering season, and form. Because mainland Chinese media have long used "紫荆花" in line with the Basic Law's wording to refer to Hong Kong's city flower, many people mistakenly believe that Hong Kong's city flower is the genus-Cercis 紫荆, rather than the genus-Bauhinia 洋紫荆.
• In mainland Chinese botanical and horticultural literature, the Bauhinia is more commonly known as "红花羊蹄甲" (hong hua yang ti jia), which is also its formal Chinese name in reference works such as the Flora of China — a synonym for the "洋紫荆" name used in Hong Kong, adding a further layer of difficulty in identification for outside observers.

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# V. From city flower to currency and flag: the public symbolisation of a hybrid tree

The Bauhinia's path from "a chance-found wild hybrid" to Hong Kong's most ubiquitous public symbol went through three key "elevations," on a clearly documented timeline:

• According to the official page of the Hong Kong Monetary Authority^※, the Bauhinia-design coin series was issued in batches starting January 1993, with the five-dollar and two-dollar coins issued first, followed by the one-dollar, fifty-cent, and twenty-cent coins in October 1993, a new ten-cent coin in May 1994, and finally the ten-dollar coin, the last to appear, in November 1994 — replacing the previously used Queen's-portrait coin series. This coin issuance preceded the 1997 transfer of sovereignty by three to four years, making it the earliest large-scale appearance of the Bauhinia design in physical circulation, ahead of the formal adoption of the regional flag and emblem.
• The designer of the five-petalled white blossom on the regional flag and emblem was Hong Kong architect Tao Ho (1936–2019). According to the official "Makers" entry at M+ Museum^※, Tao Ho graduated from Williams College in the United States and subsequently studied at Harvard's Graduate School of Design under modernist architecture figures including Walter Gropius; he was a founder and one of the principal architects of the Hong Kong Arts Centre. According to a publicly circulated account of his design process, he reportedly picked up a Bauhinia blossom in a garden and, observing the dynamic sense created by the five interlocking, rotationally symmetric petals, conceived the design of five petals arranged clockwise on the flag and emblem, each bearing a red star; this design was adopted by the Third Session of the Seventh National People's Congress in April 1990, and came into effect on 1 July 1997 alongside the establishment of the Hong Kong Special Administrative Region.
• In this way, a hybrid tree that cannot "naturally reproduce" due to its sterility instead achieved the greatest possible "reproduction" through human institutional design — first spreading across Hong Kong's streets by cutting, then being printed as a design on every coin and every regional flag, becoming one of the most frequently seen visual symbols in the city.

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# VI. HKU and the city flower: the Lung Fu Shan Environmental Education Centre

HKU's connection to this "city flower" is not only geographic coincidence, but also institutional:

• HKU's Lung Fu Shan Environmental Education Centre, located on the hillside above HKU's main campus, "includes the Bauhinia — Hong Kong's floral emblem — in its 'Ecology Codex' materials^※, as part of its public environmental-education content.
• This makes HKU one of the official institutions telling the story of Hong Kong's city flower — the flower was born in Pok Fu Lam, where HKU stands, and knowledge about it is in turn communicated to the public by HKU's own environmental education centre, a fitting circularity.
• Further still, the key scientific study that "verified the identity" of the Bauhinia was itself produced at HKU. According to the author information on the 2005 American Journal of Botany study of its hybrid origin^※, one of the paper's authors, Carol P. Y. Lau, was affiliated with the Department of Ecology & Biodiversity, The University of Hong Kong — meaning that the now-established scientific conclusion that the Bauhinia is "entirely sterile, the hybrid offspring of two species," was originally worked out inside HKU. From the discovery site, to the propagation site, to the location where the science that ultimately "verified its identity" through molecular evidence was produced, this city flower's ties to HKU run the entire chain from field to laboratory.

This connection is worth dwelling on a little further. The flower on Hong Kong's city emblem, regional flag, and coat of arms appears daily on government documents, passports, coins, and countless public occasions; and its "birthplace" in Pok Fu Lam, its "birth certificate" (the earliest scientific description and naming), and even its present-day public science communication are all bound up with HKU in numerous ways. Few connections between a university and a city's core symbol are closer or more concrete than this one. When visitors look up and see the Bauhinia in bloom on HKU's campus, what they are seeing is not merely an ornamental tree, but a piece of history in which "a wild tree on the Pok Fu Lam hillside" became "a shared symbol for seven million people" — and HKU sits at the very origin point of that history. The geographic coincidences on this hillside do not end with the city flower: sharing the Pok Fu Lam area with the Bauhinia are Béthanie, left behind by the Missions Étrangères de Paris, and the water-supply heritage buildings on HKU's heritage trail that were unexpectedly preserved by a century-old choice of campus site (see "Walking HKU") — three threads, all interwoven on the same hillside.

Naming note. This piece is documented research (not legend), reported on the facts and marked "Corroborated by multiple sources"; the Governor after whom the tree is named, and Tao Ho, designer of the regional flag, are both historical figures named in a positive context, recorded per the naming rules in sections 00–12. Proper nouns relating to the French mission, plant species, and institutions are reproduced as given. The city flower's origins are reported as stated in the academic literature, the government herbarium, and HKU's environmental centre.

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# VII. What can be seen today: form, flowering season, and the trouble of city-wide "mistaken identity"

The exact fate of the "single original tree" in Pok Fu Lam can no longer be verified, but its vegetative-propagation descendants have long since spread across Hong Kong — what they look like and when they bloom is, in fact, the part of this story easiest to verify in person, on campus and in the street, today.

• According to the official "flower-viewing bulletin" page of the Leisure and Cultural Services Department^※, the Bauhinia is an evergreen tree of the Caesalpiniaceae family, reaching up to 10 metres in height, flowering mainly from November to March — precisely the coolest, most pleasant season in Hong Kong; the blossoms are large, purplish-red, with deep purple streaks on the upper petals, a striking appearance that is also the direct source of the "ornamental value" cited when it was chosen as city flower.
• According to the same official page^※, the Leisure and Cultural Services Department manages more than 1,600 parks and gardens across Hong Kong, with the Bauhinia listed among its commonly recommended species, alongside the pink trumpet tree, Bauhinia purpurea, and the queen's crepe myrtle as popular species for public greening — meaning that today, outside HKU's campus, a clone descendant of this "single tree" can likely be found in almost any park managed by the department anywhere in Hong Kong.

The Bauhinia family also includes two close relatives often planted alongside it on Hong Kong streets, and often mistaken for it by passers-by: Bauhinia purpurea and red-flowered Bauhinia purpurea — the three are similar in flower colour and shape and not easily told apart by eye, yet are three distinct species botanically, with Bauhinia purpurea in fact being one of the parent species of the Bauhinia (see Section II). This "family resemblance" problem, together with the cross-genus confusion between "紫荆花" and "洋紫荆" described in Section IV, forms two overlapping layers of "mistaken identity" in this city flower's history — one across family and genus between Cercis and Bauhinia, the other among close relatives within genus Bauhinia itself — together illustrating a phenomenon not uncommon in botany but not widely appreciated by the public: that a tree printed on the regional flag and emblem, appearing daily on coins in people's wallets, is one most Hong Kong residents may not actually be able to pick out at a glance from its close relatives on the street.

The spread of this tree has also not stopped at Hong Kong's borders. According to the Wikipedia entry on the Bauhinia^※, it has reportedly been widely cultivated across Hong Kong Island from the original tree at the Hong Kong Botanic Gardens since 1914, and has since been introduced to overseas regions with similar climates, most commonly Southern California — where, due to mild, largely frost-free winters similar to Hong Kong's climate, the Bauhinia is widely used as a park and street tree, often listed in local horticultural catalogues under the name "Hong Kong Orchid Tree." A hybrid oddity born beside the ruins on a Pok Fu Lam hillside thus, by human hand and cutting, "cloned" its way from the very hillside on which HKU stands to street greenery on the other side of the Pacific.

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# Unconfirmed / pending verification

• The exact year of discovery (1880 vs. early 1880s): according to the official Hong Kong Herbarium page, quoting the 1903 annual report^※, the original report states "twenty to thirty years earlier," i.e., roughly between 1870 and 1880. This piece follows the academically common formulation "around 1880," while noting that the source itself carries roughly a decade of uncertainty.
• The specific location of the "abandoned building" (partly clarified): Wikipedia records it simply as near an abandoned building in Pok Fu Lam; according to the official Hong Kong Herbarium page, quoting the original text of the 1903 annual report^※, the more precise location is the ruins of a house near the seashore around Mount Davis. Whether this is the same site as the later precursor of University Hall (Douglas Castle / Nazareth House) has no direct source confirming it; this piece states only geographic proximity and draws no causal conclusion.
• The name of the first discoverer: all sources record only "a French missionary," with no source identifying the person by name; as no reliable source could be found, this piece makes no speculative identification.
• The rigour of the claim that "all Bauhinia in Hong Kong descend from the same tree": based on the sterility and hybrid-origin research, this is described as "very likely," not as an absolute assertion; the 2025 T2T genome study further explains the sterility mechanism at the chromosomal level, but its samples were taken in Shenzhen rather than from the original Hong Kong tree, so this piece continues to describe it as "very likely," without an absolute claim.

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# Further reading

• Walking HKU — two heritage trails, thirteen monuments, and the university "with the most ghost stories" — HKU's heritage trail in the same Pok Fu Lam / Lung Fu Shan area, including Béthanie and the water-supply heritage sites that intersect geographically with this piece
• Campus geography — the full geographic context behind the choice of the Pok Fu Lam campus site
• Campus buildings and landmarks — the architectural history of University Hall (originally the French mission's Nazareth House)
• Museums and campus ecology — an overview of HKU's campus ecological resources

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