B08 NOTES ON PONDWEEDS. 
P. plantayineus Ducros. — This species is much dwarfed in the 
and-form, but in other respects it remains so little altered from its 
ordinary state that no special description is required. The leaves 
re remar. ini 
respect resembling certain leaves of P. varians, noticed later on. 
After  pitobea Ba the tufts come feebly, something in the 
way of those of P. flwitans, and perhaps the leaves of these later- 
produced see are slightly more coriaceous. The land-form of 
this species seems to stand apart with that of fluitans in never pro- 
ducing lower saves reduced to a thickened midrib. 
P. heterophyllus Schreb. — This species not only throws up 
ee sects from the buried stolons, but its already produ ced sub- 
When le qui in an i ar state of growth, however, the 
already nay leaves usually perish, and are sueceeded by little 
rosettes of leaves at each ‘soint “of the branches. This is also a 
eitude in the allied forms hereafter mentioned under the names 
of P. varians and P P. nitens ? 
ve seen flower-spikes produced on a branches in P. 
heterophyllus when the plant has been growing for some time in the 
free air, but have not met with any that have pestnhas fruit in this 
condition. It seems quite possible that in damp situations fruit 
might be Bes in which case alone ae we call a Potamogeton 
truly amphibio 
The ona of this and the succeeding members of the hetero- 
phyllus saan are so variable that it is useless to attempt to give a 
detailed n of them at present-—each form presents a 
peculiar iol d will require a few general remarks ; but until 
their usual aayuntis states have been fully worked out it would be 
§ to enter into minute details. These imperfectly-known 
variety 
an undescribed variety 
between P. nitens ey heter il t P. nitens Web.( aggre aie), 
These three gies ee 5 inks 
heterophyllus and P. Zizi on the other. With the i they are 
a by a Ser which seems to be P. coriaceus No 
a Morong (in lite itt.). — This plant is considered by the 
Rey. te Moroag to be identical with the American plant 
In its subaérial state it certainly is the most remarkable sgt 
ts lthy p of operate extreme ae t and heat. 
s of J’. varians (on the bottom of a 
own to me in i 
Thave gathered h 
perfect]: 
