TETRANDRIA. TETRAGYNIA. Potamogeton. 257 
long, branched, leafy. Leaves reddish green, very entire, slightly scored, 
alternate. Sheath-scales widely spear-shaped. Fruit-stalks axillary, 
solitary, nearly as long as the leaves ; rather thick. Spike dense, reddish, 
FI. Brit. 
Long-leaved Floating Pond-weed. Welsh: Dyfr-llys amryliw. 
In slow streams, ditches and lakes not unfrequent. In ditches in 
marshy ground near Beverley. Mr. Teesdale. Lilleshall mill-pool, 
Shropshire. Rev. Mr. Williams. At Scole, Norfolk. Mr. Woodward. 
FI. Brit. In Whey Sike on Teesdale Forest; and the ditches com¬ 
municating with Hell Kettles. Mr. E. Robson. Winch Guide. Abound¬ 
ing in the river Blythe by Halesworth. Hooker. In the Clyde at JDalbeth. 
Mr. Hopkirk. In ditches and lakes near Forfar. Mr. JDon. FI. Lond. 
Braint-river, rivulet in Bryngola demesne, Llangwillog, Anglesey. Welsh 
Bot. P. July—Aug. E.) 
P. perfolxa'tum. Leaves heart-shaped, embracing the stem, (uniform, 
all submersed. E.) 
E. Bot. 168— FI. Dan. 196—Hod. 589. 3—Ger. Em. 822. 3—J.B. iii. 778. 
2 — Pet. 5. 6— If. Ox. v. 29. row 2. 3. at p. 596. 
Leaves heart-egg-shaped, very pellucid, like green oiled silk; brittle when 
dry. Blossoms yellowish brown, on an oblong-ovate spike. 
Perfoliate Pond-weed. (Welsh : Dyfr-llys trydwll. E.) Slow rivers 
and ponds, common, but th q fruit-stalks the only part which rises above 
the surface of the water. P. June—Aug. 
P. lu'cens. (Leaves elliptic-lanceolate, pointed, membranous, stalked, 
repeatedly triple-ribbed, all submersed. Spike dense, many- 
flowered. E.) 
C E.Bot. 376. E.)— Kniph. 5— FI. Dan. 195—Pef. 5. 5— J. B. iii. 777. 1— 
Dod. 582.2 — Ger. 822. 4— II. Ox. v. 29. 4. at p. 596. 
{Leaves egg-spear-shaped, flat, attenuating into leaf-stalks, beautifully 
green and pellucid, like those of the preceding species; sometimes eight 
inches long, and one and a half broad, remarkably reticulated by nu¬ 
merous transverse veins. Blossom reddish. 
(Shining Pond-weed. Welsh: Dyfr-llys disclaer. E.) Rivers and ponds. 
P. June—July. 
P. den'sum. Leaves egg-shaped, tapering to a point; opposite, 
crowded: stem dichotomous: spike four-flowered. 
(E. Bot. 397. E.)— J. B. iii. 777. 2. 
( Plant rather small, of a brighter green than some other species. Leaves 
wholly submersed, somewhat recurved, an inch or an inch and a half 
long, crowded together towards the end of the stem. Head of flowers 
quadrangular, (as in Adoxa moschatellina), rising above the water during 
impregnation, after which, as Smith observes, it is borne down by the in¬ 
creasing branches, and ripens its seed below. E.) 
Lesser Water Caltrops. Frogs’ Lettuce. Close-leaved Pond- 
weed. (Welsh: Dyfr-llys tewdws. E.) Ditches and slow streams. 
P. May—June. 
P. cris'pum. Leaves spear-shaped, alternate, upper ones opposite- 
waved and serrated, 
VOL. II. s 
