特徵描述
作者
YANG, Yuen-Po
型態特徵
Annual or perennial dioecious or polygamous fresh or saltwater herbs. Leaves radical or cauline, alternate, opposite or whorled, linear, lanceolate, elliptic or cordate, sessile or petiolate; petioles usually sheathing. Axillary scales present, 2-numerous. Flowers actinomorphic, unisexual or bisexual, enclosed in a bifid spathe or within two opposite bracts. Spathes sessile or long pedicellate. Sepals 3, valvate, green; petals 3, sometimes reduced to 2, imbricate, colored, or absent. Stamens 3-many; anthers 2-celled, longitudinally dehiscent; filaments slender. Ovary inferior, apex sometimes beaked, 1- or incompletely many-celled, parietal placenta protruding nearly to the center of ovary; styles mostly united, stigmas entire or bifid; ovules numerous. Fruit linear or ovoid, irregularly dehiscent. Seeds numerous, filiform or ovate; testa glabrous or echinate; endosperm absent; embryo straight.
屬
Sixteen genera, about one hundred species, tropical and temperate; seven genera in Taiwan.
參考文獻
Hydrilla 水王孫屬
作者
YANG, Yuen-Po
型態特徵
Submersed dioecious freshwater herbs. Stems terete, elongate. Leaves 3-6 per whorl, sessile, linear, serrate. Flowers unisexual. Staminate spathes solitary, axillary, each enclosing a single flower. Staminate flowers short pedicellate, globose, liberated from spathe and floating to water surface at anthesis; sepals 3, broadly ovate, convex; stamens 3, opposite sepals; anthers stalked, laterally dehiscent. Pistillate spathes cylindrical, solitary, axillary, sessile. Pistillate flowers pedicellate; sepals 3; petals 3, shorter and narrower than sepals; ovary inferior, cylindrical, with a filiform beak; stigmas 3. Fruit cylindrical. Seeds 1-3, ellipsoid.
