(4) 水蕨
Ceratopteris thalictroides (L.) Brongn.
水蕨科 (Parkeriaceae)
英文名 (English name): Floating Fern, Water Fern
Status in China: Vulnerable (VU). Wild plant under State protection (category II).
Description: Aquatic or semi-aquatic herbs. Rhizome short, erect, rooting in mud. Leaves clustered, dimorphous; stipes green, fleshy, hollow, variable in length according to the depth of water; sterile leaves bipinnatifid, usually 20-30 cm long; the lobes of the pinnae sometimes lobed again; fertile leaves usually longer than sterile leaves, bipinnate; pinnules divided into linear lobes, the ultimate lobes 1.5-4 cm long and about 2 mm wide, edges reflexed, thin translucent and colorless. Sori borne along the longitudinal veins and protected by the reflexed edges of the ultimate segments of pinnules.
Distribution: Sham Chung, Lai Chi Chong, Kam Tin, Plover Cove, Po Toi Island. S and SW China; tropical and subtropical regions throughout the world.
Habitat and Ecology: In ponds, paddy fields and other marshy or flooded areas.
The species represents a special living form of ferns, and is thus of great botanical interest. The leaves and stems can also be used medicinally. Although the species is widely distributed in tropical and subtropical regions, it has a special habitat requirement and in recent years its distribution area and population size are decreasing.
References:
秦仁昌、邢公俠，
1990: 中國植物誌
3（1）: 275，圖版
77：1-4。科學出版社。北京。
Edie, H. H., 1977: Ferns of Hong Kong, 241. Hong Kong Univ. Press, Hong Kong.
So, M.L., 1994: Hong Kong Ferns, 29. The Urban Council, Hong Kong.