(32) 海南杯冠藤
Cynanchum insulanum (Hance) Hemsl.
蘿藦科Asclepiaceae

英文名 (English name): Insular Swallow Wort

中國境內現狀：需予關注(LC)
Status in China: Least Concern (LC)

形態特徵: 纖細草質藤本，除莖節、葉柄和葉緣被短柔毛外全株無毛。葉對生，長圓狀戟形至三角狀披針形，長2-3.5厘米，寬0.5-1.5厘米，頂端銳尖，基部近心形或截平；側脈每邊約5條；葉柄長約1厘米。傘形花序腋生，遠短於葉，有花4-5朵；萼內基部有腺體5個；花冠綠白色，裂片長圓形，長約3毫米；副花冠杯狀，薄膜質，頂端淺10裂；花粉塊長圓形；花藥近四方形。蓇葖果單生，披針形，長4.5-5厘米，直徑8毫米。種子長圓形，種毛長2厘米。

地理分布: 西貢大灣。廣東、廣西、海南。

生境與生態：生於海邊沙灘。花期：5-10月；果期：10-12月。

本種在香港僅見於西貢大灣，具有科學研究價值。生長點均在大浪灣「具特殊科學價值地點」之內，受到保護。可嘗試進行遷地保育。

Description: Herbaceous vines, glabrous except for pubescent on stem nodes, petioles, and leaf margin. Leaves opposite, oblong-hastate to triangular-lanceolate, 2-3.5 cm long and 0.5-1.5 cm wide, apex acute, base subcordate or truncate; petioles 1 cm. Inflorescences umbel-like, axillary, much shorter than leaves, 4- or 5-flowered. calyx with 5 basal glands adaxially; corolla greenish white, lobes oblong, ca. 3 mm long, acute; corona cupular, thin membranous, apex 10-lobed; pollinia oblong; anthers nearly square. Follicles solitary, lanceolate, 4.5-5 cm long, 7-8 mm wide, Seeds oblong; coma ca. 2 cm long.

Distribution： Sai Kung (Tai Wan). Guangdong, Guangxi, Hainan.
　　

Habitat and ecology: On sandy beach. Flowering: May-Oct.; fruiting: Oct.-Dec.
　　

Known only from Sai Kung, the species is rather rare in Hong Kong and is valuable for biodiversity research. The locality of its occurrences is within Tai Long Bay Site of Special Scientific Interests (SSSI) under protection. Ex-situ conservation measures could be explored.

參考文獻 (References):
蔣英、李秉滔，1987：廣東植物誌1：507，圖575。廣東科技出版社，廣州。