Bauhinia blakeana Dunn, Hong Kong Orchid Tree
The flower of Bauhinia blakeana was adopted as the emblem of
Hong Kong in 1965 and since 1997 has been part of the flag of the SAR.
The tree was originally described as a new species in 1908 after being
discovered on the shore of Hong Kong Island near Pokfulam around 1880
and
was named after a Hong Kong governor Sir Henry Blake who had a strong
interest
in botany.
Hybrid
origin of “Bauhinia blakeana”
(Leguminosae: Caesalpinioideae),
inferred using morphological, reproductive and molecular
data Lau, C.P.Y., Ramsden, L., & Saunders, R.M.K. (2005) American Journal
of Botany 92:3 525 - 533.
Bauhinia blakeana
(Leguminosae subfam. Caesalpinioideae tribe Cercideae), or the Hong
Kong Orchid
Tree, is of great horticultural value. It is completely sterile and is
shown
here to be the result of hybridization between the largely sympatric
species, B.
purpurea and B. variegata.
Although the analysis of patterns of
morphological variation revealed only a few examples of phenotypic
intermediacy, study of intersimple sequence repeat (ISSR) markers
enabled
unequivocal identification of the parental species due to the presence
of
additive inheritance of alleles and the absence of any bands that are
unique to
B. blakeana. Investigation of
aspects of the reproductive biology of the
taxa furthermore revealed that the parental species are largely
xenogamous,
have flowering periods that overlap seasonally and temporally, and
share common
pollinators. Evidence is provided to show that B. blakeana is not
naturally stabilized and is only maintained horticulturally by
artificial
propagation. It is therefore recommended that the hybrid be regarded as
a
horticultural cultivar rather than a naturally occurring species; a new
cultivar name, Bauhinia ‘Blakeana’, is accordingly validated.
Leaves, The tree is of medium size with alternate large heart shaped leaves with 2 lobes and veins radiating from the base of the leaf. The margin is entire and the surfaces smooth and hairless. Size ranges from 8 - 15 cm in diameter petiole to 5cm long.
Flowering, from November to March. Calyx tubular, corolla of five petals coloured a deep purple. Stamens five. Ovary superior.
Fruit, only rarely observed dark pod to 30cm long, 2cm wide.