NAIADACE^E. 35 



England. Perennial. Autumn. 



A small slender plant 9 to 18 inches long. Leaves rarely above 

 1^ to 2 inches long, the lower ones bearing considerable resemblance 

 to those of P. acutifolius, the upper to those of P. rufescens in minia- 

 ture. Peduncles }j to 2 mches long, slender. Head of flowers rarely 

 60 much as ^ inch long. Although Mr. F. ]\I. Webb was kind enough 

 to send me numerous fresh specimens of this plant from Anglesea, 

 gathered as late in the year as September, I have never seen the fruit, 

 as all Mr. Webb's specimens were in flower. 



A very distinct species, which has been called in question, from the 

 Anglesea plant being combined with forms of P. heterophyllus, 

 P. nitens, and P. polygonifolius. Smith appears to have really known 

 the plant, though he has erroneouslj' given two Scotch localities on the 

 authority of Hooker's " Flora Scotica." 



Lanceolate Pondweed. ' 



SPECIES Vni._POTAMOGETON HETEROPHYLLUS. Schreb. 



Plate MCCCCVI. 



RdcJi. Ic. Fl. Germ, et Helv. Vol. Vn. Tabs. XLI. XLII. XLIH. Figs. 71 to 78. 



Billot, n. GaU. et Germ. Exsicc. No. 1066. 



P. gramineus, Fries. Mant. i. p. 36, and Summ. Veg. Scand. 68 (67). Kocli. Syn. 



Fl. Germ, et Helv. ed. ii. p. 777. Gron. & Godr. Fl. de Fr. Vol. III. p. 314. 



Crep. Man. Fl. Belg. ed. ii. p. 302 (non Linn. Sp. PI. nee Herb. !). 



Stem wiry, much branched, the lower branches barren. Leaves 

 mostly alternate, submerged, sessile, not at all amplexicaul, spreading 

 or very slightly recui*ved, nearly flat, short, elUptical-strapshaped or 

 oblong-strapshaped, rather gradually attenuated at each end, often more 

 or less undulated, not denticulate at the margins, translucent, with 7 

 to 11 longitudinal ribs connected by numerous oblique veins, and with 

 several rows of rather elongate-cancellate areolations along the sides of 

 the midrib ; upper leaves opposite, sometimes floating, and then Avith 

 long petioles, oval or oblong-elliptical, rounded or abrupt at the base, 

 rarely attenuated into the petiole, coriaceous, of the same texture as 

 the petiole, with numerous longitudinal ribs connected by numerous 

 cross veins, which are indistinctly perceptible if the leaf be held against 

 the light, when also the small areolation is indistinctly perceptible 

 distributed equally over all the leaf : sometimes the upper leaves are 

 translucent and subsessile, and similar to the lower ones, except that 

 they are more narrowed towards the base. Stipules small, except the 

 upper ones, which are broad, acute, not winged on the back, scarcely 

 scarious, except at the edges, and with numerous sti'ong longitudinal 



