NAIADACE. 37 
narrowed at the base, though not distinctly stalked (in continental spe- 
cimens they are said to be oblong-lanceolate, contracted into a petiole, 
and coriaceous. Gren. & Godr.). Stipules small, except the upper ones, 
which are rather large, acute, not winged on the back, scarious with 
numerous strong longitudinal fibres. Peduncles axillary and terminal, 
rather short, moderately stout, very slightly thickened towards the 
apex when in fruit. Sepals with their lamina transversely roundish- 
rhombic. Fruiting-spike dense, oblong, rather few-flowered. Nuts 
olive, small, acuminated, slightly compressed, nearly straight along the 
upper margin, semicircular and 3-keeled on the back, terminated by a 
short beak forming a continuation of the upper margin. Plant olive 
dull green, turning darker when dry; the leaves somewhat shining. 
In lakes and rivers. Rare. Tl irst recorded as British from speci- 
mens found in a large lake a short distance from the sea, at Castle 
Gregory, near Brandon Mountain, co. Kerry, from whence I have been 
favoured with fresh examples by Dr. D. Moore; Askog Loch, Isle of 
Bute (Mr. G. E. Hunt) ; River Tay, near Perth (Mr. John Sim) ; 
Loch Lee, Nairn (Mr. W. Stables) ; Coltfield, Elgin (Mr. Wilson of 
Alves). 
Scotland, Ireland. Perennial. Late Summer, Autumn. 
Stems 1 to 2 feet long, thicker and much less branched than in 
P. heterophyllus, from which it also differs, at least judging from Dr. 
Moore’s specimens, collected in September 1866, by sending forth in 
autumn from the axils even of the upper leaves numerous slender 
stolons similar to those of Epilobium obscurum: I have not seen 
stolons from the uppermost leaves in any other British Potamogeton. 
The leaves are intermediate in appearance between those of P. hetero- 
phyllus and the long-leaved form of P. perfoliatus, and those on the 
main stem are 1} to 3 inches long, folded so as to have a gutter in the 
middle, and more or less curved backwards. Peduncles 1 to 3 inches 
long, less thickened upwards than in P. heterophyllus, although they 
are so to some extent, when in fruit. Fruiting-spike } to 3 inch long. 
Fruit considerably smaller than that of P. heterophyllus, and in Dr. 
D. Moore’s specimens of a yellowish-olive. 
I have not seen either British or European specimens with coria- 
ceous floating leaves, but I have some continental examples with the 
upper leaves oval, attenuated at each end, and shortly stalked, though 
their texture is similar to that of the lower ones. There is no doubt, 
however, that the plant sometimes produces coriaceous floating leaves, 
like those of the preceding species. 
Shining Pondweed. 
German, Gldnzendes Samkraut. 
