NAIADACEX, 29 
Var. y is found on almost every heath, and is the commonest form 
of Potamogeton in the whole country, extending north to Orkney. 
This has the leaves all similar, and often grows in mud without any 
water. 
In Glen Devon, near Dollar, I have found a form near var. y, with 
the upper leaves nearly round, and deeply cordate at the base, and 
with larger, blunter, and more membranous stipules than in the ordi- 
nary form. 
Oblong-leaved Pondweed. 
German, Lingliches Samkrautgewichse. 
SPECIES UL—POTAMOGETON PLANTAGINEUS. Ducros. 
Pirate MCCCCI. 
Tteich. Ic. Fl. Germ. et Helv. Vol. VII. Tab. XLV. and XLVI. Figs, 82 to 85, 
Billot, Fl. Gall. et Germ. Exsice. No. 651. 
P. coloratus, Wallr. Fries, Summ. Veg. Scand. p. 68 (67). 
P. Hornemanni, Meyer. Koch, Syn. Fl. Germ. et Helv. ed. ii. p. 777. 
Stems round, simple or nearly so. Lower leaves alternate, sub- 
merged, very shortly stalked, oblanceolate or oval, on rather long stalks 
and abruptly attenuated into the petiole; upper leaves opposite, 
rising out of the water, oval or ovate-oval or roundish-oval, frequently 
subcordate at the base; all pellucid and membranous, with numerous 
longitudinal ribs connected by transverse veins, which are very con- 
spicuous if the dried leaf be held against the light, when the rather 
minute areolation is clearly perceptible all over the leaf between the 
ribs. Stipules large, blunt, not winged on the back, scarious. Peduncles 
axillary, slender, not enlarged towards the apex. Sepals with their 
lamina roundish-rhombic. Fruiting-spike cylindrical, many-flowered, 
dense. Fruit green, very small, semicircular-ovoid, compressed, nearly 
straight on the upper margin, semicircular and faintly keeled on the 
back, with a short beak forming a continuation of the upper margin. 
Young leaves bright grass-green, older ones olive. 
In shallow pools and ditches. Local, but widely distributed, 
especially in fenny districts. In Scotland I have only found it in 
' Guillon Ponds, Haddingtonshire; but it occurs also near Berwick, and 
at Oban in Argyleshire. Rather rare, but generally distributed in 
Treland. 
England, Scotland, Ireland. Perennial. Summer, Autumn. 
Very similar in habit to P. polygonifolius; but the lower leaves are 
less distinctly stalked, and the upper ones have the lamina gradually 
or suddenly contracted into the petiole, which is slightly enlarged 
