750 NAIADACE. | Potamogeton. 
long. Perianth-segments rhombic-orbicular. Fruit small, about 
;i5 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. Handb. 
N.Z. Fl. 279, 742 (not of Schreber). P. natans var. australis, Kirk 
ex A. Bennett in Journ. Bot. xxv. (1887) 177. 
NortH anpD SoutH Isuanps, Strwart Istanp: 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, Choiz, 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, 
4-tin. broad, linear-ligulate, obtuse or emarginate at the tip, 
membranous, 3- or 5-nerved with or without finer parallel veins 
between, transverse veins few; stipules free, at length conspicuously 
lacerate. Peduncles stout, erect, usually shorter than the leaves, 
1-3in. long; spike short, oblong, about $in. long. Fruit broadly 
obliquely ovoid, subcompressed, ;4,in. long, back rounded, beak 
short, thick.—Hook. f. Fl. Nov. Zel. 1. 236, and ii. 3386; A. Bennett 
in Journ. Bot. xxv. (1887) 178. P. gramineus, Hook. f. Handb. 
N.Z. Fl. 279 (not of Linn.). BP. obtusifolius, Benth. Fl. Austral. 
vil. 172 (not of Mert. and Koch). 
NortH anp SourH Is~tanps: 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. obtuszfolius, 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 sub- 
merged, alternate, sheathing at the base, 2-4 in. long by 34,-;4 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 14—2 in. long, 
of distant whorls ot flowers. Fruit rather large for the size of the 
plant, about gin. long, turgid, obscurely keeled on the back, 
slightly convex in front, rugose when dry, beak very short.— Hook. 
f. #l. Nov. Zel. ii. 336; Handb. N.Z. Fl. 279; Benth. Fl. Austral. 
vil. 173; A. Bennett, Journ. Bot. xxv. (1887) 178. 
