482 
CT. NA1ADACE.E. 
[ Potamogeton. 
almost equals P. lucens. Stipules large, lower ones sometimes 3 
inches long, white, tinged with red, not green, and without the crests 
or wings observable in the two next. 
12. P. longifulius Gay ? (long-leaved P.) ; leaves entire all 
elongato-lanceolate nearly sessile but attenuate below apiculate 
and flat at the end with several longitudinal fine nerves spring- 
ing from the prominent mid-rib connected by transverse veins, 
stipules winged, peduncles very long thickened upwards, spikes 
with a few subverticillate distant flowers. E. B. S. t. 2847. 
Lougli Corrib, Galway, Ireland. 7,8. — “ Nearly allied to P. 
pralongus, but has not the amplexicaul and hood-tipped leaves of that 
plant Bab. What the Irish plant may prove to be, when found in 
other localities, it is impossible to say. The foreign and true species 
of the same name has the leaves often suddenly acuminate, with 
sometimes a long point, and the spikes are cylindrical and densely 
flowered, as in P. lucens, from some forms of which it does not appear 
to differ; Chamisso and Schlechtendal, indeed, unite the two; and 
even Reichenbach (Ic. FI. Germ. vii. p. 25), although he figures 
them as distinct, seems to admit that P. longifolius is sometimes only | 
to he distinguished by its longer and thinner bright green finally | 
blackening leaves (not yellowish green or olive, as in P. lucens), 
which have a thicker midrib and finer reticulation. Mr. Bentham 
also unites the Irish plant to P. lucens, along with P. lanceolatus and 
P. rufescens, while he retains P. hcterophyllus as a distinct species. 
13. P. lucens L. (shining P.) ; leaves stalked minutely 
denticulate elliptic-lanceolate flat at the end mucronate or 
suddenly acuminate with sometimes a long point with several 
longitudinal nerves springing from the prominent midrib con- 
nected by transverse veins, stipules winged, peduncles elon- 
gated thickened upwards cylindrical many-flowered. E. B. t. 
376. 
Lakes, pools, and streams, common. 7£. 6.7. — The largest of 
our species, and very beautiful in the reticulation of its leaves. Sti- 
pules large, with two prominent wings or crests at the back, as in the 
last species. Upper leaves smaller than the lower ones, and all sud- 
denly contracted towards the point. Coriaceous leaves are very 
rare ; these are ovato-lanceolate, moderately acute, and less evidently 
stalked than in P. heterophytlus ; Chamisso and Schlechtendal place 
it along with those species which have sometimes floating and coria- 
ceous leaves, and change its name to P. Proteus, considering P. 
lieternp/iyl/us a variety of it. The decidedly stalked floating leaves of 
this last appear to indicate a distinction, but aquatic plants of all kinds 
are extremely liable to vary according to their place of growth. 
***** Leaves alternate, upper ones floating, broader than the others. 
Stipules free. 
14. P. heterophijllus Schreb. (various -leaved P.) ; submerged 
leaves sessile lanceolate attenuate at both ends apiculate denti- 
