Potamogeton.j TETRANDRIA — TETRAGYNIA. 69 



accompanied by many parallel oblong reticulations, as is well observed 

 by Smith. 



5. P. acutifolius. Link, (^sliarp-leaved Pofid-iveed); leaves li- . 

 near acuminate with 3 principal and numerous close parallel in- 

 terniediate nerves occupying the whole surface, spikes oval com- 

 pact about equal in length with the short peduncle. Hook, in E. 

 JBot. SuppL t. 2609. 



Rarey Hitherto only found in marsh-ditches at Amberley, Henfield 

 and Lewes, Sussex, Mr Borrer. Fl. July. If. — The numerous, closely 

 placed, parallel nerves well distinguish this and the following species 

 from their congeners. 



6. P. zoster cefolius, Schum. (grass ivrach-like Pond-weed^ ; 

 leaves broadly linear acute with 3 principal and numerous close 

 parallel intermediate nerves occupying the whole surface, spikes 

 cylindrical upon long peduncles. Reichenb. Iconogr. t. 175. f. 

 SOS. Cham.et Schkcht. in Linn(ca,v. W. p. 182. t. 4.f. 10. E. 

 Bot. SuppL t. 2685. — P. cuspidatus, Schrad. — E. Fl. v. i. p. 234. 



Rare ? Rivulet at Hovingham, Yorkshire. Lakes of Rescobie and 

 Forfar. Fl. July. %. — Larger than the last; \\\i\\ peduncles 3 — 4 in- 

 ches long, and spikes cylindrical, an inch in length. 



**** Leaves alternate, ovate, lanceolate or oblong, all submersed; 

 stipules free. 



7. P. crispus, L. (curled Pond-iveed); leaves lanceolate waved 

 and serrated 3-nerved, fruit beaked. E. Bot. t. 1012. 



Ditches and rivers, frequent. FL June, July. V-. 



8. P. peifolidtics, L. (perfoliate Pond-tceed); leaves cordate- 

 ovate amplexicaul 7-nervod with smaller intermediate nerves. 

 E. BoL L 168. 



Ditches and lakes, frequent. FL July. li. — Peduncles rather short, 

 thick. Spikes oblong-ovate. 



9. P. lucens, L. (^shining Pond- weed) ; leaves elliptic-lanceolate 

 niucronate with several opposite pairs of parallel nerves spring- 

 ing from the midrib connected by reticulations, spikes cylindri- 

 cal many-flowered. E. Bot. t. 376. 



Lakes, pools, and streams, abundant. FL June, July. If. — The largest 

 of our species, and very beautiful in the nervation of its leaves. Chamisso 

 and Schlechtendal include this in a division of the Genus which has 

 sometimes floating and coriaceous leaves [folia accessoria), (as it is found 

 by 3Ir Wilson at Llyn Maclog) they change its name to P. Proteus, 

 and consider the P. heterophyllus a variety of it. To me they appear 

 distinct ; but aquatic plants of all kinds are extremely liable to vary. 

 Stipules large and with 2 prominent wings at the back. Stem thinner 

 than the flower-stalk, which is thickened upwards and about the same 

 length as the spike. Spikes cylindrical, 2 inches long. Nerve promi- 

 nent on both sides of the leaf. Upper leaves smaller than the lower 

 ones, and all suddenly contracted towards the point. — Coriaceous leaves 

 rare, ovato-lanceolate, moderately acute, less evidently stalked than in 

 P. heterophyllus ; foliage more crowded and stipules larger and (in pro- 

 portion) narrower than in that species. Spikes twice as long. Wilson, 



