角果藻科 jiao guo zao ke
Guo Youhao (郭友好)[1]; Robert R. Haynes[2], C. Barre Hellquist[3]
Plants submerged in fresh or brackish water. Rhizomes creeping, usually slender, branched, rooting at nodes. Stems elongated, slender, much branched. Leaves submerged, sessile, alternate, subopposite, or crowded at nodes, linear, with conspicuous midvein, sheathing at base margin entire. Plants monoecious. Flowers axillary, minute, unisexual, solitary or in cymes. Male flower solitary, pedunculate, without perianth; stamens 1(or 2); filament slender; anthers 2-thecous; pollen grains globose or nearly so. Female flowers with a cupular perianth, sessile; carpels 1–9, free; ovule 1, pendulous; styles simple, slender, elongated; stigmas usually obliquely peltate. Fruitlet achene or nutlike, slightly compressed, subsessile or stipitate, abaxially keeled; keel usually winged. Seeds without endosperm.
One extremely polymorphic species: cosmopolitan; one species in China.
Several species have been recognized by some authors and the taxonomy of the genus needs considerable reevaluation.
角果藻属 jiao guo zao shu
The description and distribution as for the family.
角果藻 jiao guo zao
Zannichellia palustris var. pedicellata Wahlenberg & Rosen.
Stems 3–20(–50) cm, 0.3–0.5 mm in diam. Leaves 2–10 cm × 0.3–0.5 mm, apex acuminate; sheaths usually free from leaf base, stipuliform, membranous, evanescent. Anthers 0.6–1 mm; filaments ca. 3 mm; Carpels usually 3 or 4. Fruitlet often curved, reniform to semilunate, 2–2.5 mm, abaxially remotely cristate-dentate, long beaked. Fl. and fr. spring–autumn. 2n = 12, 24, 28, 32, 36.
Freshwater or brackish water. Most of China. Anhui, Hebei, Heilongjiang, Hubei, Jiangsu, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Taiwan, Xinjiang, Xizang, Zhejiang [Cosmopolitan].
The specimens with obliquely peltate stigma, fruitlets reniform and 4–6 in pedicel are described as Zennichellia palustris var. pedicellata. But specimens from China are variable in the shape of the stigma, characters of fruit and degree of stipitation. Because of this, the plants are here regarded as forming a single variable species.
[1] Herbarium or 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.