ZANNICHELLIACEAE  

Submerged annuals, occasionally perennating, monoecious. Roots 1-3 per node, simple, densely covered with long roothairs, penetrating substratum spirally. Rhizome creeping, matted, sympodial. Stems simple or sparsely branched, erect. Leaves ternate, opposite or alternate, linear, sessile, with a free cupular sheath subtending axils, or leafbase expanded into a folded sheath forming auriculate stipules above; axillary scales 2, minute. Flowers unisexual, solitary, or with a collateral vegetative bud or one of opposite sex beside it. Male flowers ephemeral, on long filaments (pedicels); anthers 4- or 8-sporangiate, with an apical knob; pollen globose, copious. Female flowers surrounded by a spathe, solitary or pseudo-umbellate; carpels (1-)4 or 5(-9), surrounded by a closely appressed flask-shaped 'perianth'; style exserted, tubular; stigma spoon- or funnel-shaped, large, with wavy membranous margins, ephemeral; ovule pendulous. Fruit a somewhat bean-shaped drupelet, stipitate and crowned with persistent style, pectinate on dorsal and occasionally on ventral side. Seed with a long, spirally coiled hypocotyl. x = 6 (7, 8) (polyploidy).

Small, creeping, coastal, submerged annuals. Roots 4-7 from a node, simple, long, densely covered with long root-hairs. Rhizome branched, slender, with a deciduous, lanceolate, amplexicaul scale from each node. Stems simple, erect, up to 150 mm long, filiform. Leaves usually aggregated above, filiform-setaceous, up to 50 mm long; sheaths folded, membranous, about 5 mm long, forming a forked appendage above, 2-3 mm long, becoming frayed with age. Flowers in clusters. Male flowers solitary, on a pedicel which elongates up to 4-5 mm during anthesis so that anther is just exserted, often with 3, as yet undeveloped, female flowers beside them; perianth a small 3-toothed cup, with the 1-thecous anther sessile or subsessile; pollen globose. Female flowers usually 3 together; (1-)3-carpellate; carpels stipitate, each enfolded in a membranous bract, narrow-ovoid, unilocular, with long style and saucer-shaped apical stigma. Fruit a stipitate, cylindrical, slightly oblique, smooth drupelet crowned with persistent, pin-like style and stigma base.