Cymodoceaceae Vines

Marine, rarely estuarine, perennial herbs, submerged to intertidal, dioecious. Rhizome creeping, herbaceous monopodial and rooting at each rhizome node or woody sympodial and rooting at certain rhizome nodes. Roots often branched, fleshy to woody; scales scarious, ovate or elliptic. Stems erect, sparsely to much branched, ringed with open or closed leaf scars, with several leaves at branch ends. Leaves distichous or clustered, with distinct blade and sheathing base; sheath open, auriculate, ligulate; blade linear, flat or terete, entire or denticulate, glabrous, with 3 or more longitudinal parallel veins; apex very variable in outline; tannin cells numerous; stomata absent. Flowers solitary and terminal on short branches, or arranged in a cymose inflorescence, enclosed by bracts or by normal or reduced leaves; perianth absent. Male flowers subsessile or pedicellate; stamens 2, shortly stalked or subsessile; anthers tetrasporangiate, attached either at the same or slightly different levels, longitudinally dehiscent; pollen filiform. Female flowers sessile or shortly pedicellate; carpels 2, free; style either long and undivided, or short and divided into 2 or 3 filiform stigmas. Fruit 1 or 2, either with a hard pericarp, indehiscent or viviparous.