113 
NOTES ON PONDWEEDS. 
By Aurrep Fryer. 
Potamogeton Zizi Roth.—Stem stout, much branched at the 
base, rootstock producing numerous permanently ly gran a barren 
branches; fruiting branches ultimately ascending to the ace 
with many lateral branches starting at acute angles, and with a auada 
coriaceous floating leaves on the flowerless as well as on the flowering 
nate, t tim 
alterate or onesie more distineily stalked ; eee floating, 
coriaceous or subcoriaceous, flat, entire ; or mem ranous, very long- 
stalked; petiole 3-8 in. ; lamina 1-5 in., slightly decurrent, 
narrowed into the petiole, which is of the same substance an 
colour as the midrib, suddenly contracted towards the tip, which © 
has the edges slightly involute when dry, forming a blunt point. 
Stipules blunt; lower small, clasping ; “upper large, free above, 
“Sis app rarely s subscarious, two-keeled or two-winged on the 
back, uppermost often cymbiform. Podundles longer than the 
leaves at é their base, often pene clusters, stout, praia: 
upwards, 8-5 in. long. Spike dense, eylindri cal, 14-2 long 
Drupelets small in proportion to the size of the plant, ‘latocally 
compressed, with a prominent sometimes winged keel, and prominent 
lateral ridges; beak short, forming a continuation of the straight upper 
margin. Colour of the whole plant dark green or green, in deep 
water Pans s yellowish olive-green. 
he ve description is made unusually full and compre- 
8. as forms of P. Zizii, but some of which may apr 
prove to be sufficiently distinct a — segregation. One of 
these ee the P. coriaceus of Nolte, is probably the typical 
or central form of the lucens group as represented in Britain; but 
as the plant is little known at pre esent I must reserve its life- 
n at the tim 
flowering branches usually start at acute angles, instead of at right 
angles as in P. lucens, giving quite a differe al to the p 
: aes | 
of undue sane and -~ tend +o 
[Aprit, 1887.] 
JOURNAL OF ve : 
