' 258 TETRANDRIA. TETRAGYNIA. Potamogeton. 
Curt. 5—( E.Bot. 1012. E.)— FI. Dan. 927— Ger.Em. 824. 2— Park. 1248. 
2— Pet. 5. 9 — J. B. iii. 778. 1—Clus. ii. 252. 2—Ger. Em. 824. 3 —Park. 
1248. 3—Pet. 5. 8. 
Stems long; much branched; flatted. Leaves two inches long; alternate; at 
the forks of the stem opposite; sessile; nearly strap-shaped; semi-trans- 
jiarent, crisped at the edges. Spikes as long as the fruit-stalks. Blos¬ 
soms six to ten; white or reddish; in short loose spikes. 
(Var. 2. P. serratum. Huds. P. crispum (5. Sm. Leaves less obviously 
undulated; opposite. E.) 
Greater Water Caltrops. Curled Pond-weed. (Welsh: Dyfr-llys 
crych . E.) Ponds and slow streams; common. P. May—July.* 
P. compres'sum. Leaves strap-shaped; obtuse, (spikes about four- 
flowered. E.): stem compressed. 
(E. Bot. 418. E.)—F7. Dan. 203—Pet. 5. 10. 
( Plant small. Stipules large and conspicuous, whitish. Stem wavy. E.) 
Leaves narrower than in the preceding, not waved, (two or three inches 
long, an eighth of an inch broad. E.) Spikes shorter than the fruit- 
stalks. Blossom greenish. 
Flat-stalked Pond-weed. Slow streams and ditches. 
P. June—July. 
(Var. 2. Leaves broader and longer. Relh. 
Queen’s Green, &c. Cambridge. 
Mr. Dawson Turner suspects from the great difference of habit, as well as 
size, that this may prove a distinct species. E.) 
(P. cuspida'tum. Leaves linear, with an oblique taper point: three 
principal ribs, and numerous intermediate ones, all distinct: 
stem compressed. 
Loes. Pi'uss. t. 66. 
Larger than the last, with which it has, in England, always been con¬ 
founded. Leaves not rounded at the end, but taper off rather suddenly 
and obliquely into a terminal point, formed of the substance of the leaf: 
lateral ribs only two, one at each side, half way between the mid-rib and 
the margin; often very inconspicuous, but there are numerous inter¬ 
mediate ribs all over the leaf, which do not occur in P. compressum. 
Pointed-leaved Pond-weed. P. cuspidatum. Schrad. P. compressum. 
Teesd. Linn. Tr. v. 2. In ponds and rivulets. In a rivulet at Hoving- 
ham, Yorkshire. Mr. It. Teesdale. In the lake of Rescobie, and also in 
the lake of Forfar. Mr. G. Don. Sm. E.) 
P. pectina'tum. Leaves bristle-shaped, parallel, near together, two- 
rowed, (sheathing at the base : spikes interrupted. E.) 
(E. Bot. 323— FI. Dan. 186. E .)—Lob. Ic. i. 790— Ger. Em. 828. 4— Pet. 
5. 13— Pluk. 216. 5. 
(The plant does not bear blossoms unless it grow in stagnant water, but 
in running streams the general herbage is larger. FI. Brit. E.) j Flowers 
five or six on each fruit-stalk. Stackh. ( Root arising from a small 
(Ducks greedily devour this plant, and may be usefully employed to clear ponds in¬ 
fested with it. E.) 
