42 ENGLISH BOTAXT. 



but often tlicre are leafy branches in place of the axillary peduncles, 

 l-'ruitinjx-spike 1 to 2 indies lonp:, consequently shorter than that of 

 I*, lucens, but much tliicker. JS'uts larufer than in any of the other 

 British species, nearly { inch lontj, by i inch deep, keeled when dry. 

 Prof. Babington states that when fresh they are rounded, and rarely 

 keeled on the back ; but a large number of specimens sent me from 

 Iioekland Broad, Norfolk, by the Rev. Kirby Trimmer, had the fi'esh 

 fruit furnished with a very acute keel, and the Rev. W. W. Newbould 

 informs me that this is also the case in the plant found at Oxford. 



The j^lant from the Waveney at Bungay, collected by Professor 

 Babington, has the dried fruit smaller than that fi'om Norfolk, more com- 

 pressed, with a fiiinter central, and much more prominent lateral keels, 

 in this agreeing with the plant from Loch Lee, Nairn, and Guthrie 

 Bum, Forfar, from both of which stations I have specimens in fruit. 



Long-stalked Pondweed. 

 French, Potainot flexiieux. German, Gestrcolctes Sanikraut. 



SPECIES XIII.-PO TAMO GETON PERFOLIATUS. Lmn. 

 Plate MCCCCXII. 



Reich. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XXIX. Fig. 53. 



Stems slender, sparingly branched, the lower branches barren, the 

 upper branching more or less dichotomous. Leaves all similar, the lower 

 ones alternate, the uppermost and those at the base of the forks of the 

 stem opposite, submerged, sessile and amplexicaul, spreadmg-ascending, 

 flat, ovate or oblong-lanceolate, cordate at the base, obtuse or subacute, 

 not apiculate nor cuspidate nor hooded at the apex, not serrate at the 

 margin, with 5 to 7 strong ribs and several fainter intermediate ones 

 connected by rather distant transverse veins, and with narrow bands of 

 very elongate cancellate areolation at the sides of the ribs. Stipules 

 small, usually absent or evanescent, except in the uppermost leaves and 

 those at the forks of the stem, and often present only in the latter 

 case and in those leaves which have peduncles in their axils, subacute, 

 sc^rious, with a few distant slender fibres. Peduncles terminal be- 

 tween the forks of the stem and axillary, rather short, slender, equal 

 in thickness. Sepals with their lamina suborbicular. Fruiting-spike 

 rather dense, shortly oblong-cylindrical, rather few-flowered. Nuts 

 olive, rather large, not acuminated and but slightly compressed, curved 

 alonfT the upper margin, semicircular and very bluntly keeled on the 

 back, terminated by a very short central beak. Plant bright green, 

 turnino- olive and sometimes black and dim in drymg. 



In ditches, slow streams, and lakes. Rather common, and generally 

 distributed, extending north to Orkney. 



