34 EXCLISII EOTAXT. 



stipules are much narrower than in P. hetcrophyllus ; the peduncles 

 also are much longer and more slender and much less thickened 

 towards the apex. 



The plant ironi the BojTie agrees perfectly with North American 

 specimens of P. Lonchitis, Tztckerman, in the Herbarium of the late 

 M. Gay, atKew; but I suspect this is the same as P. salicifolius, Wolf- 

 gn)i(j, of which I have not seen si)ecimens. C. J. Hartmann describes 

 a form of P. salicifolius with floating leaves, which Fries and Reichen- 

 bach do not seem to have met with. 



Willow-leaved Pondiveed. 



SPECIES vn.—PO TAMO GE TON LANCEOLATUS. Sm. 



Plate MCCCCV. 



P. nigrescens (?), Fries, Mant. iii. p. 17, Summ. Veg. Scand. pp. 68 (G7) and 214 

 (ex descrip. non Herb. Norm.). 



Stem filiform, fragde, much branched, the lower branches barren. 

 Leaves mostly alternate, submerged, sessile, scarcely at all amplexicaul, 

 not recurved, rather short, strapshaped, rather abruptly attenuated at 

 each end, flat, not undulated, not denticulate, translucent, with 3 or 

 5 longitudinal ribs connected by few transverse veins, and with 

 several rows of greatly elongated canccllate areolations along the mid- 

 rib ; upper leaves opposite, sometimes floating, but even then scarcely 

 stalked, oblanceolate or oblanceolate-strapshaped, gradually attenuated 

 towards the base, subcoriaceous or translucent, of the same texture as 

 the very short petiole, with 7 or 9 ribs, and numerous cross veins, which 

 are conspicuous if the leaf be held against the light, when also small 

 areolation is very distinctly perceptible all over the leaf, with larger 

 areolations along each of the ribs : often the upper leaves are similar 

 to the lower, except that they are broader, and more narrowed towards 

 the base. Stipules free from the petiole, small, narrow, acute, not 

 winged on the back, scarious, with few fibres. Peduncles (always?) 

 axillary, rather short, not tliickened towards the apex. Spike ovoid- 

 oblong, very short. Sepals with their lamina rhombic-orliicnlar. Nuts 

 unknown ( ?) — " keeled with faint lateral ridges " {Bah.).* Plant dark 

 green, often turning blackish in drying. 



In the river Lligwy between Bodafon and Lligwy, Anglesea. Smith 

 says it was sent him from lakes in North Wales by the Piev. H. Davdes, 

 probably from the station mentioned above. 



* I do not know whether the fruit described by Professor Babington is that of the 

 Anglesea plant, which alone belougs to this species. 



