30 ENGLISH BOTANY. 



towards the apex, and not of uniform width, as in P. polygoni-, 

 folius ; the lamina of all the leaves, when held against the light, 

 shows a delicate areolation between the veins, the cells being largest 

 along tlie sides of the ribs. The fruit is about j'g inch long, consider- 

 ably smaller than in the last species, green, not red, with the upper 

 margin straighter, and terminated by the beak, Avhich in i'. polj'goni- 

 folius is situated moi*e nearly in a prolongation of the axis of the 

 fruit. In both P. polygonifolius and P. plantagiiieus the fruit is 

 marked with a lateral ridge on each side of the keel. 



The leaves vary in breadth, as in P. polygonifohus : in some Guern- 

 sey specimens they are suborbicular. 



Plantain-leaved Pondweed. 



French, Poiamot plantain. Gorman, Wcfjelreithldttonges Samlcraut, 



SPECIES IV.-POLYGONUM RUPESCENS. Schrad. 

 Plate MCCCCH 



Edch. Ic. n. Germ, et Helv. Vol. VII. Tab. XXXH. Kg. 5G to 58. 



Billot, Fl. Gall, et Germ. Exsicc. No. 650. 



P. fluitans. Sm. Engl. Bot. ed. i. No. 18G6 (non Both.). 



P. alpinns, Ball. Crep. Man. Fl. Belg. ed. ii. p. 302. 



Stems round, simple or nearly so. Lower leaves alternate, sub- 

 merged, sessile, strapshaped-elliptical, or oblong-elliptioal, attenuated 

 at the base and apex, not denticulate, translucent, with numerous faint 

 longitudinal ribs connected by transverse veins, and with several rows 

 of large cancellate areolations along the midrib ; upper leaves opposite, 

 floating or rising out of the water, stalked, oblanceolate or obovate or 

 obovate-elliptical, gradually attenuated into the short petiole at the base, 

 subcoriaceous, of the same texture as the petiole, mth the ribs and cross 

 veins rather conspicuous if held against the light, when minute areola- 

 tion is indistinctly perceptible all over the leaf between the ribs : more 

 rarely the upper leaves are submerged, pellucid, and similar to the 

 lower ones in shape and texture, or in some intermediate state between 

 this and that previously described. Stipules large, blunt, not winged 

 on the back, scarious. Peduncles axillary, rather slender, not enlarged 

 towards the apex. Sepals with their lamina roundish. Fruiting-spike 

 oblong-cyUndrical or cylindrical, many-flowered, dense. Fruit reddish- 

 fawn colour, rather small, oval-ovoid, acuminated at the apex, very 

 convex on the upper margin, semicu'cular, and sharply keeled on the 

 back, with a rather promuient recurved subtermuial beak. Plant 

 tinged with reddish-brown, especially when dry. 



Var. a, genuinus. 



Lower leaves pellucid; upper leaves subcoriaceous, floating. 



