(31) 香港巴豆
Croton hancei
Benth.
大戟科(Euphorbiaceae)

英文名 (English name): Hong kong Croton

中國境內現狀:極危 (CR)
Status in China: Critically endangered (CR)

形態特徵: 灌木或小喬木;嫩枝和花序均被貼伏的星狀毛。葉密生於小枝頂端,紙質,長圓狀披針形,通常長8-12厘米,寬2-4厘米,頂端漸尖,基部漸狹,全緣或邊緣有細鋸齒,兩面無毛,基部中脈兩側通常各有1枚具柄的杯狀腺體;葉柄短,被毛。總狀花序頂生,長約3厘米;雄花多朵,密生,花梗短,花蕾時球形,直徑約2毫米;萼片卵形;花瓣狹小;雄蕊約16枚,花絲被綿毛;雌花通常1朵生於花序基部;萼片長圓形,長4-5毫米;子房近球形,密被毛,花柱3枚。
  

地理分布: 本種為香港特有種,僅見於青衣島。
  

生境與生態:生於山地林中。花期:6月。
  

本種屬稀有種,首次約於1850年在香港島發現,其後於1997年在青衣島再被發現。對於研究香港和中國植物區系有一定的科學價值。分布區面積小,種群個體少。原生地可建議列為「具特殊科學價值地點」。此外,漁護署已進行遷地保護,採種育苗,城門標本林內有栽培。

Description: Shrubs or small trees; young branches and inflorescences covered with appressed stellate hairs. Leaves crowded near apex of branches, papery, oblong-lanceolate, usually 8-12 cm long, 2-4 cm wide, apex acuminate, base attenuate, entire or serrulate, glabrous on both surfaces, with a stipitate cupular gland on each side of midrib at base; petiole short, hairy. Racemes terminal, ca. 3 cm long. Male flower: numerous, dense; pedicels short; flower buds globose, 2 mm in diam.; sepals ovate; petals narrow and small; stamens 16, filaments woolly hairy. Female flower: usually solitary at base of inflorescences; sepals oblong, 4-5 mm long; ovary subglobose, dense hairy, stigmas 3.

Distribution: Endemic to Hong Kong and restricted to Tsing Yi Island.

Habitat and ecology: In montane forest. Flowering: June.

Discovered in Hong Kong Island around 1850 and re-discovered in Tsing Yi Island recently, this rare species is of special botanical interests. It is endemic to Hong Kong and has a very restricted distribution with only a few small populations. Consideration should be given to list the locality with a high density of this species as a Site of Special Scientific Interests (SSSIs). AFCD have been actively propagating this plant and reintroducing it into the wild. Ex-situ conservation has also been carried out and living specimens are displayed in the Shing Mun Arboretum.

參考文獻 (References):
丘華興,1996:中國植物誌44(2): 136. 科學出版社,北京。
Bentham, G., 1861: Flora Hongkongensis: 308. Reeves, London.