(21) 香港細辛
Asarum hongkongense S. M. Hwang & T. P. Wong Siu
馬兜鈴科(Aristolochiaceae)

英文名 (English name): Hong Kong Asarum

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

形態特徵：多年生草本，具根狀莖，根稍肉質，芳香。葉近革質，卵狀心形或卵形，長6-11厘米，寬5-8厘米，頂端急尖，基部深心形，邊緣稍背卷，密被緣毛，兩面無毛，上面光亮，葉脈基出，7條；葉柄長12-30厘米。花單生，紫綠色；花梗無毛，長1.5-4厘米。花被喉部多少縊縮，內面無膜環，筒部闊卵形或近球形，檐部開展，3裂，裂片闊卵形，長約1.5厘米，寬約1.2厘米；雄蕊12，花絲短於花藥。子房近上位，花柱6，頂端2裂，柱頭卵形。
　　

地理分布：香港特有種，僅見於大嶼山。
　　

生境與生態：生於海拔500-800米的林下；花期:2-4月。
　　

本種為香港特有植物，於1988年在大嶼山首次發現，對研究香港和中國植物區系均有一定科學價值。此外，本種具有潛在的藥用和觀賞價值。分布區非常狹窄，且種群小。但生長地點位於大嶼山郊野公園內而受到保護。可嘗試遷地保育。

Description: Perennial herbs, with long prostrate rhizomes; roots more or less fleshy, aromatic. Leaves slightly leathery, ovate-heart-shaped or ovate, 6-11 cm long, 5-8 cm wide, apex acute, base deeply cordate, margin slightly revolute, densely ciliate, glabrous on both surfaces, glossy above, basal veins 7; petioles 12-30 cm long. Flowers solitary, purplish green; pedicels glabrous, 1.5-4 cm long; throat more or less constricted, without membranous circle inside; tube broadly ovoid or subglobose; limb patent, 3-lobed; lobes broadly ovate, ca. 1.5 cm long, 1.2 cm wide; stamens 12, filaments shorter than anthers. Ovary nearly superior, styles 6, apex bifid, stigma ovate.
　　

Distribution: Endemic to Hong Kong, only found in Lantau Island.
　　

Habitat and ecology: In thickets or thin forests on hillslopes, at altitude of 500-800 m. Flowering: Apr.-Jul.
　　

This species was first discovered in 1988 in Lantau Island with one small wild population. As an endemic species and the only representative of the genus Asarum in Hong Kong, it is of value for further scientific research. The plant also has potential medicinal uses. The locality is within Lantau Country Park under protection. Ex-situ conservation measures could be explored.

參考文獻(References)
黃淑美、黃蕭德平，1990：香港細辛屬一新種。植物分類學報 28 (5): 406-408.
李甯漢、劉啟文(主編), 1997: 香港中草藥 7: 16-17。商務印書館，香港。