932 TETRANDRIA— TETRAGYNIA. Potamoeeton. 



;■? 



Mr. Davoll. 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 G 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 /\ nutans, elliptic-oblong, 

 bluntish; tapering at the base in to footstalks, extremely various 

 in length. Stipulas 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- 

 cimens, and resembling P. coloratura, Ft. Dan. t. 1449^, what- 

 ever that may be. 



6. P. lucens. Shining Pond-weed. 



Leaves elliptic-lanceolate, pointed, membranous, stalked, 

 repeatedly triple-ribbed, all submersed. Spike dense, 

 many-flowered. 



P. lucens. Linn.Sp. PL 183. WUld.v.1.714. Fl. Br. 194. Engl. 

 Bot. v.C). t.376. Hook. Seot. 58. FL Dan. t. 195. 



P. n. 846. Hall. Hist. v. 1. 376 ; exel. the syn. of Linnceus. 



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

 Syn. 148. 



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



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



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

 sime crenatis. Pluk. Amalth. 177 ? Dill, in Raii Syn. 150 ? 



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



Long Pond-weed. Petiv. H. Brit, t.o.f.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 

 thejlowcrs. Stem not much branched. Lea res about 4 inches 

 long, all nearly alike, more or less acute, tipped with a small 

 point ; their colour olive green, now and then reddish in the 

 upper ones ; their base usually tapering into the footstalk, some- 

 times rounded ; their margins more or less undulated, becoming- 

 plaited when pressed, and the edge is rough, or very finely ere- 

 nate, but this last character varies. What is most characteristic 

 is the strong network, formed by the numerous transverse veins, 

 connecting the 5 or 7 longitudinal ribs ; and especially the union 

 of the side ribs to the middle one, a considerable way above the 



