45 ENGLISH BOTANY. 
base, obtuse, subapiculate, translucent, with 3 (rarely 5) strong ribs, 
without faint ones between them. Stipules rather small, subacute, 
scarious, with numerous slender longitudinal fibres. Peduncles ter- 
minal between the forks of the stem, equalling or slightly exceeding 
the spike, rather slender, not thickened upwards. Sepals with their 
lamina deltoid-rhombic. Pistils 4. IFruiting-spike oblong-ovoid, dense, 
rather few-flowered. Fruit moderately large, brownish-olive, slightly 
compressed, not acuminated, convex on the upper margin, on which 
there is no tooth, semicircular and 3-keeled on the back, terminated by 
a very short central straight beak. Plant rather dark green, sometimes 
tinged with red, retaining its colour when dried. 
In ditches and ponds. Rather scarce, but widely distributed. I 
have seen specimens from the counties of Sussex, Kent, Surrey, 
Hereford, Warwick, Salop, Chester, Lancaster, and Kincardine, and 
there is good authority for extending its range south-west to Dorset 
and Devon. Rare, and local in Ireland, where it occurs both in the 
south and north, but has not been observed in the midland counties. 
England, Scotland, Ireland. Perennial. Summer. 
Usually a smaller and more branched plant than the two preceding 
species, and differiyg greatly in its slender stem, which is scarcely 
flattened, and in the absence of faint intermediate ribs in the leaves, 
which are also distinctly narrowed towards the base. The leaves are 
2 to 3 inches long by } to } inch broad, and are not acuminated into 
an acute point at the apex, where the margins meet in the form of a 
wide gothic arch. Peduncles, exclusive of the spike, } to } inch long. 
Spike about } inch long. Nuts } inch long, in form resembling those 
of P. zosterifolius, but more convex on the upper or inner margin. 
This is a well-marked species, which only a superficial examination 
could confound with either of the two preceding species. I have never 
seen more than 3 ribs on the leaves of this plant, but Koch says they 
are 3- to 5-nerved. 
Grassy Pondweed. 
French, Potamot a feuilles obtuses. German, Stumpfblattriges Samkraut. 
SPECIES (?) XIX—POTAMOGETON MUCRONATUS. Selvad. 
Pratre MCCCCXVIII. 
Reich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XXIV. Fig. 42. 
P. compressus, Sm. Engl. Bot. ed. i. No. 418. Engl. Fl. Vol. I. p. 233. Bab. Man. 
Brit. Bot. ed. vi. p. 365. Reich. l.c. p. 15. 
P. pusillus, var. major, Fries. Nov. Fl. Suec, p. 48, and Summ. Veg. Scand. p. 69 
(68). Hook. & Arn. Brit. Fl. ed. viii. p. 480. 
P. Oederi, “ Meyer,” Boreau, Fl, du Centr. de la Fr. ed. iii. Vol. II. p. 601. 
Stem 4-sided, considerably compressed, slender, not foliaceous, 
