角果藻科 jiao guo zao ke
Authors: Youhao Guo, Robert R. Haynes & C. Barre Hellquist
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.
The Angiosperm Phylogeny Group [APG] (Bot. J. Linn. Soc. 161: 105-121. 2009) included this family in the Potamogetonaceae. However, for the Flora of China, we treat the families separately.
Several species have been recognized by some authors, and the taxonomy of the genus needs considerable reevaluation.
Zhou Lingyun, You Jun & Zhong Xiongwen. 1992. Zannichellia. In: Sun Xiangzhong, ed., Fl. Reipubl. Popularis Sin. 8: 102-107.