NOTES ON PONDWEEDS. 809 
Hipth out of water by the stems of these plants as they advance 
growth, then presents the appearance of a climbing plant. 
Tn Sick meuatone it produces flowers, but I have never seen frui 
sh except in submerged plants. 
S 
bead-like tubers from the land-forms (as before oo are most 
feel produced. Here perhaps we have the most real advance 
wards an amphibious Potamogeton, as not only is growth success- 
fally kscom plished i in the open air, but an de scpalty successful storing 
of t 
season results from that growth. In this way it seems quite possible 
or P. varians and its allied forms to exist for season after season 
grows are a Ms or a great part : every summer. In one ditch I 
kne 
the form of a rosette. ese lmear leaves are succeeded by a pair 
of broader linear-lanceolate, or oblong, acutely pointed muarene 
membranous translucent leaves, and to these miooeed two or more 
coriaceous, ovate or elliptical, or : wagers leav 
The shallow-water form of this is well figured in Reichenbach, 
‘Icones,’ v. 7, pl. 38, from a specimen supplied by Nolte himself. 
The land-form of our fenland plant, whatever it may be, has sub- 
orbicular coriaceous —— and the lower ones are reduced to 
‘‘phyllodes,” as in P. natans and P. heterophyllus. 
P. Zizii Roth. This species . Sagar a well-marked land-form. 
The stolons from which it springs are often a foot or more deep in 
