水蕹科 shui yong ke
Guo Youhao (郭友好)[1]; Robert R. Haynes[2]; C. Barre Hellquist[3]
Herbs, perennial, freshwater aquatic. Rhizome tuberous, with fibrous roots. Leaves submerged and/or floating, basal, long petiolate, broadly elliptic to linear, with few primary veins and numerous transverse secondary veins, sheathed at base. Inflorescence usually a simple or 2-forked terminal spike; spathe present, but usually very early caducous. Flowers hermaphroditic or unisexual. Perianth segments 1–3 or rarely absent, white, yellow, mauve, or bluish violet, often petaloid, persistent. Stamens 6 to many; filaments elongated, free, filiform or flattened; anthers extrose, 2-celled; opening by longitudinal slits. Carpels 3–6(–8), free or slightly united near base; ovary superior; style short; ovules 2–8 per carpel. Fruit a whorl of follicles. Seeds without endosperm; embryo straight.
Monogeneric: widely distributed in the tropical and subtropical parts of the Old World, but most numerous in tropical S Africa, Madagascar, India, Papua New Guinea, and northern Australia; only one species in China.
水蕹属 shui yong
The description and distribution as for the family.
水蕹 shui yong
Aponogeton pygmaeus Krause; A. taiwanensis Masamune.
Rhizome obovoid or elongated, to 2 cm, often with filament remnant of sheath. Petiole 9–15 cm in submerged leaves and 40–60 cm in floating leaves; leaf blade narrowly ovate to linear, 4–6 × 1–2 cm, herbaceous, with primary veins at base 7–9, base cordate or rounded, margin entire, apex rounded or with a blunt tip, Inflorescence to ca. 5 cm, pedunculate. Flowers bisexual. Perianth segments 2, yellow, slightly obovate, ca. 2 mm. Stamens 6, filaments broadened toward base. Carpels slightly united near base, with 4–6 ovules per carpel. Fruit ovoid, 2–3 mm, with a short terminal beak. Fl. Apr–Oct.
Paddy fields, ponds, streams. Fujian, Guangdong, Guangxi, Hainan, Jiangxi, Yunnan, Zhejiang (Longquan) [Cambodia, India, Indonesia, Laos, Malaysia, Thailand, Vietnam].
The specimens of this species were incorrectly named Aponogeton natans, but the latter has reddish or purple flowers, filaments not broadened, and a longer beak. The relationship between A. lakhonensis and A. natans needs to be further studied.
[1] Herbarium of Wuhan University, Department of Biology, Wuchang, Hubei, People’s Republic of China
[2] Herbarium, Biological Sciences, Biodiversity and Systematics Department, University of Alabama, Box 870345, Tuscaloosa, Alabama 35487-0345, U.S.A.
[3] Department of Biology, Massachusetts College of Liberal Arts, North Adams, Massachusetts 01247-4100, U.S.A.