128 NAIDACEAE. [ Potamogeton. 
wnfoc.. Nak- KE 1S nus) ie 
4. P. ochreatus Raoul Choix (1846) 13, t. 7.—Stems slender, striate, 
branched, long or short according to the depth of the water. Leaves all sub- 
merged, alternate or the upper opposite, sessile, 1-4 in. long, $4 1n. 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 4 in. 
long. Fruit broadly obliquely ovoid, subcompressed, 7 in. long, back 
rounded, beak short, thick.—Hook. f. Fl. Nov. Zel. 1 (1853) 236, and 11 (1855) 
336; A. Bennett in Journ. Bot. xxv (1887) 178; Cheesem. Man. N.Z. Fl. 
(1906) 750; JU. N.Z. Fl. u (1914) t. 207. P. gramineus Hook. f. Handb. 
N.Z. Fl. (1864) 279 (not of Linn.). P. obtusifolius Benth. Fl. Austral. vii 
(1878) 172 (not of Mert. and Koch). 
NortH AND SoutH Istanps: 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. (1753) 127.—Stems long, filiform, 
much branched, often forming dense masses. Leaves all submerged, 
alternate, sheathing at the base, 2-4in. long by -;;1n. broad, very 
narrow-linear or almost filiform, upper channelled on both surfaces, lower 
flatter, 1-3-nerved with transverse veinlets ; stipules adnate with the sheath- 
ing base of the leaf. Peduncles long, slender, filiform, not thickened 
upwards; spike 14-2in. long, of distant whorls of flowers. Fruit rather 
large for the size of the plant, about }in. long, turgid, obscurely keeled 
on the back, slightly convex in front, rugose when dry, beak very short.— 
Hook. f. Fl. Nov. Zel. ii (1855) 336; Handb. N.Z. Fl. (1864) 279; Benth. 
Fl. Austral. vii (1878) 173; A. Bennett in Journ. Bot. xxv (1887) 178; 
Cheesem. Man. N.Z. Fl. (1906) 750. 
Norra Isnanp : Auckland—Waikato River and Lake Whangape, 7’. Kirk! 7. F.C. ; 
Lakes Tarawera and Rotomahana, 7’. Kirk/ mouth of Rangitikei River, Wellington, 
Cockayne. Hawke’s Bay—Tangoia Lagoon, Colenso, A. Hamilton! Cape Turnagain, 
B. OC. Aston! Sours Istanp: Canterbury—Lake Forsyth, 7. Kirk! Otago—Lake 
Waihola, and still waters of the Taieri Plain, Petrie / December—March. 
A very widely distributed plant, found in fresh or brackish waters in most parts 
of the world. It has a local distribution in New Zealand, and, although abundant in 
some localities, is absent from wide stretches of apparently suitable stations. 
3. RUPPIA Linn. 
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 want- 
ing. 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 mem- 
branous ; embryo with a large thick radicle and small incurved cotyledon. 
A genus of either one variable species or of several closely allied ones, common 
in brackish waters in almost all temperate or subtropical countries. 
