minute areolation; stipules very long and conspicuous, 3–5 in., free, acuminate. Submerged leaves wanting or if present few and reduced to long and narrow phyllodes without any lamina. Peduncles stout, 2–4 in. long, bearing a dense-flowered spike 1½–2 in. long. Perianth-segments broadly rhomboidal. Fruit ⅙ in. long, turgid, obliquely ovoid, keeled on the back when dry, beak short.—Hook. f. Fl. Nov. Zeal. i. 236; Handb. N.Z. Fl. 278; Benth. Fl. Austral. vii. 170 (in part); A. Bennett in Journ. Bot. xxv. (1887) 177.
North and South Islands: Probably not uncommon.
A widely dispersed plant, found in nearly all temperate climates. Its exact distribution in New Zealand is not yet made out with certainty, as P. Cheesemanii has been recorded in mistake for it in many localities, but I have seen specimens from both Islands.
2. P. polygonifolius, Pourr. in Mem. Acad. Toul. iii. (1788) 325.—Stem creeping at the base, long or short, simple or sparingly branched. Floating leaves on long petioles; lamina 1–3 in. long, elliptic-oblong to lanceolate, acute or obtuse, rounded or subcordate or acute at the base, not plicate, thinly coriaceous; stipules much shorter than in P. natans, 1–1½ in. long. Submerged leaves linear-lanceolate, acute. Peduncles variable in length, rather slender; spike dense-flowered, ¾–1½ in. long. Perianth-segments transversely elliptic. Fruit small, reddish, 112–110 in. long, blunt and rounded on the back, not keeled, beak very short.—Kirk in Trans. N.Z. Inst. iii. (1871) 165.
North and South Islands, Stewart Island: Ponds and small streams from the North Cape southwards, not uncommon. Sea-level to 1500 ft. December–April.
Distinguished from P. natans by the smaller and more membranous leaves, much shorter stipules, slender peduncles, and much smaller fruit not keeled on the back when dry. Several of my specimens have been examined by Mr. A. Bennett, of Croydon, whose knowledge of the genus is unrivalled, and he informs me that their identity with P. polygonifolius cannot be questioned; The species is widely spread in Europe and Asia, and has been recorded from Australia.
3. P. Cheesemanii, A. Bennett in Journ. Bot. xxi. (1883) 66.—Stems slender, striated, long or short, simple or branched. Upper leaves alternate or opposite, long-petioled; lamina ¾–1¾ in. long, elliptic-oblong to oblong or lanceolate, obtuse, rounded at the base, coriaceous, 10–16-nerved with numerous cross-veins and minute areolation; stipules broad, subacute. Submerged leaves numerous, usually alternate but sometimes opposite, shortly petioled, 2–4 in. long, ¼–¾ in. broad, oblong-lanceolate to lanceolate or linear, very thin and membranous, translucent, 5–12-nerved with rather distant cross-veins, margins often undulate or crisped, not denticulate. Peduncles variable in length, rather slender; spike dense, ½–¾ in.
