44 ENGLISH nOTANY. 



lower ones often evanescent, scarioiis, with a few distant slender fibres. 

 Peduncles terminal between the forks of the stem and axillary, rather 

 short, moderately stout, tapering towards the apex, usually curved. 

 Sepals with their lamina suborbicular. Fruiting-spike rather lax, 

 oblong-ovoid, few-flowered. Nuts fuscous-olive, rather large, greatly 

 acuminated, compressed, curved along the upper margin, rounded 

 and bluntly keeled on the back, terminated by a long slightly rc- 

 cin-ved su])ulate beak about as long as the nut itself. Plant olive, often 

 tinged wth brownish-red, especially on the stem and midrib of the 

 leaves, retaining its colour when dried ; leaves slightly shining. 



In ditches and ponds. Very common, and generally distributed, 

 except in the extreme north of Scotland. 



England, Scotland, Ireland. Perennial. Summer. 



Stems branching as in P. perfoliatus. Leaves 1 to 3 inches long, 

 remarkably undulated at the margins and tinged with reddish-brown, 

 so that the plant may be very readily recognised. Fruiting peduncles 

 1 to 4 inches long. Fruit very different from that of all the other 

 species, about i inch long, but half of this length is occupied by the 

 beak. 



The young state of this plant is the P. serratus of Hudson ; it is 

 very unlike the ordinary form, and might easily be passed over as 

 P. obtusifolius, but the leaves are more or less serrulate. A speci- 

 men of the ordmary form gathered late in August had thrown out 

 numerous branches of P. serratus from its rootstock, so it cannot be 

 considered as even a variety. 



Curled Pondweed. 



French, Pofamot crepu. German, Kraicses Samkraut. 



Section II.— OPPOSITIFOLII. 



Leaves all similar and opposite, sessile and amplexicaul, ovate or 

 lanceolate, with involute vernation. Stipules absent, except at the 

 base of the peduncles. Peduncles terminal. Spikes few-flowered, 

 very short, dense. 



SPECIES XV.— POTAfflOGETON DENSUS. Linn. 



Plate MCCCCXIV. 



Beich. Ic. Fl. Germ, et Helv. Vol. VII. Tab. XXVII. Figs. 4G to 49. 

 Billot, Fl. GaU. et Germ. Exsicc. No. 2552. 



Stems rather slender, sparingly dichotomously branched. Leaves 

 all submerged and translucent, opposite, amplexicaul, folded longi- 

 tudmally and recurved, ovate or lanceolate, acuminate, finely serrulate 



