NAIAD ACE^. 31 



Var. 3, homophyUits. 



Leaves all pellucid, none of them floating. 



In ditches and slow streams or pools. Rather local, but generally 

 distributed. It is, however, doubtful if it extends to the extreme 

 north of Scotland. Rather rare in Ireland, but occurring from south 

 to north of the island. 



England, Scotland, Ireland. Perennial. Summer, Autumn. 



Stems springing at intervals from the creeping rootstock, simple, 

 6 inches to 3 feet long. Lower leaves 3 to (i inches long ; lamina of 

 the upper or floating leaves 1 J to 3 inches long. Fruiting spil^e | to 

 2 inches long, usually much shorter than the peduncle. 



The acuminated fruit, scarcely at all compressed on the sides, dis- 

 tinguishes P. rufescens from the deep-water forms of P. polygonifolius, 

 in which also the lower leaves are more attenuated towards the base 

 and smaller, the upper ones not attenuated into the petioles, and more 

 coriaceous, the petioles much longer, and the whole plant is less tmged 

 with reddish-brown than in P. rufescens. 



Eeddisli Pondweed. 



French, Potamot rousdire. German, BuMiclies Samlcraut. 



Sub-Section II.— LUCENTES. 



Stem branched, the flowering stem giving off" barren branches in its 

 lower part. Peduncles axillary or terminal. 



SPECIES (?) v.— POTAMOGETON " SPARGANIIFOLIUS." Bah. 



Plate MCCCCin. 



Bah. Man. Brit. Bot. ed. vi. p. 363 (ex parte) (non Last. ! nee Fries T). 

 P. Kirkii, mild, ]\IS. 



Stems round, much branched ; the lower branches barren. Leaves 

 mostly alternate, submerged, sessile, very long, linear, attenuated at 

 tlie base, and more abruptly so at the apex, not denticulate, trans- 

 lucent, -with numerous longitudinal ribs connected by few and distant 

 transverse veins, and with several rows of greatly elongate-canccllate 

 areolations along the midrib ; upper leaves sometimes floating, longly 

 stalked, elliptical or oblong-elliptical, gradually or the upper ones more 

 abruptly attenuated into the long petiole at the base, subcoriaceous, of 

 the same texture as the petiole, with the ribs and cross veins conspicuous 

 if the dried leaf be held against the light, when minute areolation is 

 indistinctly perceptible all over the leaf bct\vecn the ribs : often the 



