NAIADACEiE. 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.Sc 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, turnuig darker when dry; the leaves somewhat shining. 



In lakes and rivers. Rare. First recorded as British from speci- 

 mens found in a large lake a short distance from the sea, at Castle 

 Gregory, near Brandon ]\Iountain, 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 Avhicli it also differs, at least judging from Dr. 

 Moore's specimens, collected m September 1866, by sending forth in 

 autunm 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 tlie 

 main stem are I} 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 f 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 

 theh' 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, Gldtuxndcs Samlcraut. 



