26 ENGLISH BOTANY. 



a short style, undivided. Fruit of 4 subdrupaccous achcncs, or of 

 fcnvcr by abortion. 



Herbs growing in fresh or brackish water, with submerged 

 translucent leaves with cancellate, more rarely parallel venation, some- 

 times "with the upper leaves floating and more or less coriaceous. 



Tlic dcvivation of the name of this genus of plants is from Trorafios, river, and 

 ■ytiVur, ncighboui', because it grows in or near rivers. 



Section I.— PLANTAGINIFOLIA 



Leaves all oblong or elliptical or oval, translucent, alternate, and sub- 

 merged, or the upper ones opposite and sometimes floating and 

 coriaceous, with involute vernation, with ribs connected by cross 

 veins. Stipules free from the leaves or leaf-stalks. Peduncles axillary 

 or terminaL Spikes many-flowered, more or less elongate, dense. 



Sub-Section I.— NATANTES. 



Stem simple or slightly branched towards the apex, without barren 

 branches from the lower part of the flowering stems. Upper leaves 

 stalked, coriaceous or subcoriaceous, rarely membranous or translucent. 

 Peduncles axillary. 



SPECIES L—PO TAMO GE TON NATANS. Linn. Auct. 



Plate MCCCXCIX. 



Feich. Ic. Fl. Germ, et Helv. Vol. VII. Tab. L. Fig. 89. 

 Billot, Fl. Gall, et Germ. Exsicc. No. 2381. 



Stems round, simple or nearly so. Lower leaves alternate, submerged, 

 linear, chanelled, opaque, with numerous longitudinal ribs ; upper leaves 

 floating, mostly alternate, stalked, oblong-oval or oval, subcordate or 

 rounded at the base, coriaceous, the coriaceous texture extending a 

 short distance down the petiole, with numerous ribs connected by trans- 

 verse veins which are indistinct if the dried leaf is held against the 

 light. Stipules very large, fibro-scarious, not winged on the back. 

 Peduncles axillary, rather thick, not enlarged upwards. Sepals with 

 their lamina roundish-rhomboidal. Fruiting-spike cylindrical, many- 

 flowered, dense. Fruit* olive, large, roundish-obovate, slightly com- 

 pressed, convex on the upper margin, semicircular and keeled on the 

 lowei', with a short beak forming a continuation of the upper margin. 



• In this order it is the dried fruit which is described. 



