Halophila

noun

Plants of marine waters. Rhizomes present; leaf-bearing branches arising from rhizome at each node; stolons absent. Erect stems, if present, rooted in substrate, unbranched, short; scales 2, midway or higher on stem. Leaves 2--8, terminal pairs or pseudowhorls [distichous], submersed, sessile or petiolate; blade linear to ovate, base tapering to stem; apex obtuse; midvein without lacunae along side(s), blade uniform in color throughout; abaxial surfacely without prickles; intravaginal squamules entire. Inflorescences 1-flowered or cymose, sessile; spathes not winged. Flowers unisexual, staminate and pistillate on same plants or on different plants, submersed, sessile, nearly sessile (pistillate), or pedicellate (staminate) ; petals absent. Staminate flowers: filaments distinct; anthers linear to fusiform; pollen in moniliform chains. Pistillate flowers: ovary 1-locular; styles 3--5, not 2-fid. Fruits ovoid to spheric, smooth or ridged, not echinate, dehiscing by decay of pericarp. Seeds spheric or nearly so, echinate to reticulate.