TETRANDRIA— TETRAGYNIA. Potamogeton. 231 



In ponds, ditches, and slow streams. 



In ditches, in marshy ground near Beverley, Yorkshire. Mr. Tees- 

 dale. Lilleshall mill-pool, Shropshire. Rev. E. Williams. In 

 the river at Scole, Norfolk. Mr. Woodward and Mr. D. Turner. 



Perennial. July, August. 



As large as the first species, with which it agrees in having the 

 upper leaves floating, and considerably coriaceous j but it is 

 really more akin to lucens, from which Haller had much diffi- 

 culty to distinguish our plant. He speaks of it as very com- 

 mon in Switzerland, and I have many specimens from the late 

 Mr. Davall. J. Bauhin's figure agrees far better with this than 

 with the following, to which his synonym has always been re- 

 ferred. The stem is 5 or 6 feet long. Whole plant nearly im- 

 mersed, a few of the uppermost leaves only being more or less 

 floating, during the flowering season at least. These are firm 

 and coriaceous, though less so than in P. natans, elliptic-oblong, 

 bluntish ; tapering at the base into foot -stalks, extremely various 

 in length. Stijndas sheathing. Flower-stalks axillary, solitary, 

 from various parts of the stem, slightly swelling upwards. Spikes 

 above an inch long, cylindrical, dense. The lower leaves are 

 sessile, occasionally somewhat stalked, lanceolate, mostly acute. 

 The ribs of all the leaves are distinct and separate from the very 

 bottom, by which this species essentially differs from the follow- 

 ing. All parts of the plant, especially the upper leaves, and 

 flowers, are tinged with a reddish hue, permanent in dried spe- 

 cimen:^, and resembling P. coloraium, Fl. Dan. t. 1449, what- 

 ever that may be. 



6. P. lt(cens. Shining Pond- weed. 



Leaves elliptic-lanceolate, pointed, membranous, stalked, 



repeatedly triple-ribbed, all submersed. Spike dense, 



many-flowered. 

 P. lucens. Lmn. 6p. P/. 183. Willd.v.\.1\\. Fl. Br. 194. Engl. 



Bot. V. 6. t. 37G. Hook. Scot. 58. Fl. Dan. t. 195. 

 P. n. SAC). Hall. Hist. v. 1. 376 : excl. the sijn. of Linyiceus. 

 P. aquis immersum, folio pellucido, lato, oblongo, acuto. Rail 



Sijn. 148. 

 P. longis acutis foliis. Ger. Em. 822./. 

 P. altera. Dod. Pempt. 582./. 

 P. alterum nostras, longis et obtusis splendentibus foliis, minutis- 



sime crenatis. Pluk. Amalth. 1 77 ? Dill, in Raii Spi. 1 50 ? 

 Lapathum fluitans, longo serrato folio. Bauh. Hist. v. 2. 988./. 

 Long Pond-weed. Petiv. H. Brit. t. 5./. 5. 

 In ditches, ponds, lakes, and slow streams, chiefly on a clay soil, 



frequent. 

 Perennial. June, .July. 

 Rather larger than the last, floating entirely under water, except 



\\\Qfl,owers. Stem not much branched. Leaves about 4 inches 



