NAIADE7E. 



789 



Chiefly a North American species, 

 not common in Europe, where it appears 

 to be rather a western plant. Occurs 

 in many parts of Britain. Fl. summer. 

 Sometimes the floating leaves are not 

 developed, and then it is scarce]y to be 

 distinguished from the slender P. ex- 

 cept by its larger size, with a denser 

 spike, and generally a firmer consis- 

 tence. 



Fig. 948. 



3. Shining Pondweed. Potamogeton lucens, Linn. 

 (Fig. 949.) 



(Eng. Bot. t. 376. P. longifolius, Eng. Bot. Suppl. t. 2847.) 



A large species, the leaves usually all 

 thin and under water, sessile or nearly 

 so, tapering at both ends or scarcely ob- 

 tuse, 2 or 3 to near 6 inches long, seldom 

 above half an inch broad, marked with 

 2 or 3 well-defined longitudinal nerves 

 on each side of the midrib, besides seve- 

 ral intermediate fainter ones, and a few 

 transverse reticulations. Flowers as in 

 the broad P. 



In ponds and rivers, usually rather 

 deep, generally distributed over the 

 globe, except the extreme north. Not 

 uncommon in Britain. Fl. summer. A 

 variety with the upper leaves floating on 

 the surface and shortly stalked, either 

 lanceolate or oblong, has been distin- 

 guished under the name of P. rufescens 

 (P.fluitans, Eng. Bot. t. 1286). The 

 lanceolate P. (P. lanceolatus, Eng. Bot. t. 1985) appears to be a smaller 

 state of the same species, which is always to be distinguished from the 



Fig. 949. 



