Hong Kong's national flower is the Bauhinia (to be exact it is: Bauhinia Blakeana) flower.
The following is my copy-paste work.lol. I copied and pasted it here from other sites.
The flower on the flag is the Hong Kong Orchid Tree (Bauhinia Blakeana) - named after the British Governor of Hong Kong from 1898 to 1903, Sir Henry Blake, a keen botanist who discovered it near Pokfulam, Hong Kong Island, in 1880.
The actual flowers are bright pinkish purple, not white as on the flag.
If I remember my botany it is normally sterile and can only be propagated by cuttings (there is one tree that is said to produce seeds). Actually it is neither a tree nor an orchid, it's a member of the class leguminosae (the pea family). The genus is named in honor of the Swiss botanists of the 16th and 17th centuries, the Bauhin brothers.
Graham Bartram, 20 August 2004
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The design of the flag carries cultural, political and regional meanings. The colour itself is significant: red is always the festive colour for the Chinese people, and one might remember that the People's Liberation Army was once called the Chinese Red Army. Thus, the colour conveys a sense of celebration and nationalism. Moreover, the red is identical to that used in the PRC flag, which implies the close linkage re-established between post-colonial Hong Kong and its mother country. The juxtaposition of red and white on the flag symbolises the
one country two systems political principle applied to the region, with the stylised
Bauhinia blakeana harmonising this dichotomy.
The bauhinia had been used as the official symbol of the now-defunct Urban Council since 1965 (depicted to the right). One may observe the design elements that have been incorporated into the Hong Kong flag.