Page:Manual of the New Zealand Flora.djvu/791

Potamogeton.]

Slender submerged much-branched herbs, usually growing in brackish water. Leaves alternate or opposite, filiform, with broad sheathing bases. Flowers minute, hermaphrodite, 2 or more on a spike, at first enclosed in the membranous leaf-sheath, but after flowering the filiform peduncle elongates greatly, and is either straight or spirally coiled. Perianth wanting. Stamens 2, opposite; filaments very short; anthers 2-celled, the cells distinct, opening outwards. Carpels 4; stigma sessile, peltate; ovule solitary, pendulous from the apex of the cell. Fruiting carpels stipitate, obliquely ovoid, obtuse or beaked. Seed uncinate; testa membranous; embryo with a large thick radicle and small incurved cotyledon.

1. R. maritima, ''Linn. Sp. Plant.'' 127.—Stems slender, filiform,, variable in length, 6–24 in., leafy throughout. Leaves 2–5 in. long, filiform, with broad membranous sheathing bases. Flowers 2–6 together, at first completely enclosed in the inflated leaf-sheath; but the spike gradually emerges, and is borne up to the surface of the water by the usually conspicuously spirally coiled peduncle. Ripe carpels $1⁄10$–$1⁄8$ in. long, greenish, obliquely ovoid, beaked; each one on a slender stipes sometimes more than 1 in. long.—''Hook. f. Fl. Nov. Zel. i. 236; Handb. N.Z. Fl. 279; Benth. Fl. Austral.'' vii. 174.

Slender submerged water-plants; stems filiform, branched. Leaves usually opposite, filiform, sheathing at the base; sheaths stipular. Flowers minute, axillary, monœcious, a single male and female enclosed in the membranous leaf-sheaths. Male flower: Perianth wanting. Stamen 1; filament short at first, elongating as the flower expands; anther 2–3-celled, linear, basifixed,