NAIADACE&. 41 
the leaves variable in length, and often stalked: I have little doubt 
about its being merely a variety of P. lucens. 
Long-leaved Pondweed. 
SPECIES XI.—POTAMOGETON PRALONGUS. Wulf. 
| Prare MCCCCXI. 
| Reich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XXXIIT. Fig. 59. 
Stems stout, sparingly branched, the lower branches barren. Leaves 
all similar, the lower ones alternate, the upper ones opposite, sub- 
merged, sessile and semiamplexicaul, ascending, flat, long, strapshaped 
or oblong-strapshaped or oblong, rounded at the base, obtuse, not 
apiculate nor cuspidate but hooded at the apex, not serrate at the 
‘margins, with 3 strong ribs and several fainter intermediate ones con- 
nected by numerous transverse veins, and with a narrow band of 
elongate cancellate areolation along the sides of the midrib. Stipules 
rather large, blunt, not winged on the back, subscarious, with numerous 
slender longitudinal fibres. Peduncles terminal and axillary, very 
‘long, rather stout (but not thicker than the stem), very slightly 
‘thickened towards the apex. Sepals with their lamina transversely 
roundish-oval. Fruiting-spike dense, cylindrical, many-flowered. Nuts 
green, very large, not acuminated, scarcely compressed, slightly curved 
‘along the upper margin, half-obovate and very sharply keeled or winged 
beneath, terminated by a short beak forming a continuation of the 
‘upper margin. Plant bright green, rarely tinged with red, retaining 
its colour when dry, the leaves not shining. 
In deep water, in rivers and lakes. Rather scarce, but widely dis- 
tributed on the east side of the island where it extends from Essex 
to Nairn. Except towards the east coast, it seems to be very scarce, 
and its area of distribution is bounded towards the west and north- 
west by the counties of Berks, Oxford, Stafford, Western York, 
‘(Malham Tarn, Dr. J. Windsor), and Westmoreland (Mr. Borrer). 
Very local, and rare in Ireland, where it is confined to the west and 
north. 
England, Scotland, Ireland. Perennial. Early Summer. 
A large species, with somewhat the habit of P. rufescens or 
P. lucens. The leaves on the main stem are often 4 to 6 inches long, 
those on the barren shoots smaller, all of them slightly amplexicaul, 
and slightly hooded at the apex, never cuspidate or pointed, as in 
P. lucens. Fruiting-peduncles 5 inches to 1 foot long, frequently 
several together—i.e. a terminal one, and one or two axillary ones, 
VOL. IX, G 
