Hydrocharitaceae
水鱉科
特徵描述
註：依本站目前採用的分類系統，本科部分屬在《Flora of Taiwan》中分屬不同科，因此以下依植物誌使用的科名分列特徵描述。
[ Hydrocharitaceae 水鱉科 ]
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
[ Najadaceae 茨藻科 ]
作者
YANG, Yuen-Po
型態特徵
Fragile, mostly monoecious, submersed aquatic herbs, in fresh or brackish water. Stems slender, much branched, sometimes spiny. Leaves in pseudo whorls, narrowly linear, serrulate or serrate, sessile, sheathing at base. Sheaths with 2 axillary intravaginal scales, auriculate, truncate or decurrent, serrulate. Flowers minute, 1 or 2 in leaf axil, each often enclosed in a membranaceous spathe. Staminate flowers monandrous, in a spathe, subsessile or pedicellate; perianth segments hyaline, bifid at apex; anthers sessile, 1- or 4-celled. Pistillate flowers: ovary sessile, 1-celled, carpel 1; stigmas 2 or 3, unequally divided, persistent; ovule 1, erect from base of cell. Fruit oblong or ovoid, 1-seeded, usually embraced by leaf sheath. Seeds oblong or ovoid, with a conspicuous raphe, distinctly areolate; endosperm absent.
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.
Species 2, Eurasia, Africa, India, Malaysia and Australia. One species in Taiwan.
