468 poNDWEEDs. [March, 



nomenclature of two plants is thus rendered puzzling and am- 

 biguous. It is not certain that Dillenius's figure, tab. 4;, fig. 3, 

 of his edition of Ray's ' Synopsis/ is a true representative of 

 P. grammeus ; but it is abundantly certain that it is not P. liete- 

 rophyllus, Schreber. 



The latter has the upper leaves floating, elliptical, tapering at 

 both ends, on long leaf-stalks, green in colour, and as substantial 

 as those of P. natans. The stipules are very long, and the lower 

 leaves, if they be leaves, or if not, abortive branches, are narrow 

 and cylindrical. The whole plant is slenderer than P. natans. 

 It is more like an elongated form of P. polygonifolius. Its con- 

 nection with P. grammeus is rather remote. 



9. P. sparganiifolius, Lsestadius, is one of our most recent ad- 

 ditions to this genus. It has a long slender stem, not unlike the 

 stem of the preceding, and it is also furnished with two kinds of 

 leaves ; the lower, like those of Sparganium natans, long, linear, 

 and flaccid ; the upper elliptic, lanceolate, on long stalks, taper- 

 ing at both ends, like those of P. lieterophyllus in shape, but 

 narrower, and with a more open and delicate vascular organization. 

 This is one of the rarest of our Pondweeds, and appears to be 

 limited to the north of Europe. 



10. P. lanceolatus, Sm. A specimen so named, jaewes me, i. e. 

 herbario in meo, from North Wales, probably Anglesea ; this 

 has long, slender, cylindrical stalks, with few leaves except on 

 the barren shoots ; the lowermost leaves are nearly two inches 

 long, elliptical or lanceolate, and very narrow, a little more than 

 one-eighth of an inch in breadth ; their consistency is like that of 

 the pellucid-leaved species. The peduncles are very stout, and 

 much longer than the leaves. The spikes are dense, and above 

 ail inch in length. The stipules are not above an inch long. 

 Note. This agrees with Smith's description only in the foliage. 

 (See ' English Flora,' vol. i. p. 283.) 



11. P. crispus, Linn. This well-known and distinct species 

 may be easily recognized by its crisp (wavy-edged), toothed, sessile 

 leaves, which, though usually described as lanceolate, are oblong, 

 not contracting gradually, but with an abrupt round apex ; i. e. 

 their margin is equally distant from the midrib from their base 

 to their summit, and they are from two to four inches long. 

 They are all submerged (under water), and their reticulation 

 (network) is not so close or regular as in the above-described 



