long. Perianth-segments rhombic-orbicular. Fruit small, about 110 in. long, broadly ovoid, slightly compressed, keeled on the back, beak short.—A. Bennett, l.c. xxv. (1887) 177; Cheesem. in Trans. N.Z. Inst. xvi. (1884) 410. P. heterophyllus, Hook. f. Handh. N.Z. Fl. 279, 742 (not of Schreber). P. natans var. australis, Kirk ex A. Bennett in Journ. Bot. xxv. (1887) 177.
North and South Islands, Stewart Island: Abundant throughout in streams, ponds, and lakes. Sea-level to 3000 ft. Manihi. November–March.
The most abundant species, universally distributed throughout the colony. The numerous submerged leaves and smaller floating ones at once separate it from P. natans, to say nothing of other differences. According to Mr. Bennett, it is also found in Tasmania.
4. P. ochreatus, Raoul, Choix, 13, t. 7.—Stems slender, striate, branched, long or short according to the depth of the water. Leaves all submerged, alternate or the upper opposite, sessile, 1–4 in. long, ⅛–¼ in. broad, linear-ligulate, obtuse or emarginate at the tip, membranous, 3- or 5-nerved with or without iiner parallel veins between, transverse veins few; stipules free, at length conspicuously lacerate. Peduncles stout, erect, usually shorter than the leaves, 1–3 in. long; spike short, oblong, about ½ in. long. Fruit broadly obliquely ovoid, subcompressed, 110 in. long, back rounded, beak short, thick.—Hook. f. Fl. Nov. Zel. i. 236, and ii. 336; A. Bennett in Journ. Bot. xxv. (1887) 178. P. gramineus, Hook. f. Handb. N.Z. Fl. 279 (not of Linn.). P. obtusifolius, Benth. Fl. Austral. vii. 172 (not of Mert. and Koch).
North and South Islands: Rivers and lakes from the North Cape to Otago, not uncommon. November–March.
This is a much larger and stouter plant than the northern P. obtusifolius, to which it was referred by Bentham. It appears to be plentiful in Australia, ranging from Queensland to Tasmania.
5. P. pectinatus, Linn. Sp. Plant. 127.—Stems long, filiform, much branched, often forming dense masses. Leaves all submerged, alternate, sheathing at the base, 2–4 in. long by 120–115 in. broad, very narrow-linear or almost filiform, upper channelled on both surfaces, lower flatter, 1–3-nerved with transverse veinlets; stipules adnate with the sheathing base of the leaf. Peduncles long, slender, filiform, not thickened upwards; spike 1½–2 in. long, of distant whorls of flowers. Fruit rather large for the size of the plane, about ⅛ in, long, turgid, obscurely keeled on the back, slightly convex in front, rugose when dry, beak very short.—Hook. f. Fl. Nov. Zel. ii. 386; Handb. N.Z. Fl. 279; Benth. Fl. Austral. vii. 173; A. Bennett, Journ. Bot. xxv. (1887) 178.
