290 ON A NEW BRITISH POTAMOGETON OF THE NITENS GROUP. 
Mcrae is slightly thickened above like that of typical P. nitens, and 
non-serrulate flattened leaves 
ri was first discovered by Mr. E. F. Cooper, of 
s type in Nolte’s hathaiasn the British 
Museum. Although the typical specimen differs oan the cero 
form of the plant in some slight degree, I at once saw that it is 
specifically identical with P. Cooperi, and is, with little cern a 
ween P. crispus aid <P. per oliatus, an one strongly 
confirmed by bebo 8 specific description, which I her e append :— 
‘n. 2la amogeton undulatus Wolfg.; caule compresso, 
deten utringue ‘longitudinal. fluctuante, ew eri ne posit foliis 
omnibus submersis, membranaceis, integerrimis, alternis, oblongo- 
ovatis, lanceolatis, rotundato-obtusis, apice -plahix snoplantoaru bates 
stipulis a ore ‘complanatis, cauli adpressis. Wolfe. n. 22, 
Besser n litt. 
iffert a P. erispo foliis longioribus, majoribus, integerrimis 
Gis crispatis, nee serrulatis), colore atroviridi et venis non con- 
vergentibus, sed cera oe ts striatis. Wolfg. In specim. 
nostr i Hotes desunt; folia 4-5 poll 4-4 poll. lata, majora quam in 
erispo, quidquam un lulata, sy nervia, nervis 3 fortioribus. Maxime 
sane ee P. crispo. In fluvio Waha prope Wilnam. Wolfg.” 
R. oof 8. 1 
The aly important respect in which the above description 
differs from that given of P. Cooperi is that the leaves are described as 
non-serrulate. e minutely-toothed edges of ae leaves canes 
the notice of the describer, but they are present in Wolfga 
specimen in Nolte’s herbarium, and exactly resemble those of ithe 
British ee 
Here, too, we must place P. perfoliatus var. Jacksoni F. A. Lee 
a form wall described by that acute botanist in The Botanical Recor "a 
Club Report for 1880, p. 150 :—« Leaves all submerged, alternate 
and half-clasping, yet they are not recurved in the way Scottish 
nitens at 8 he are; nor are the upper stipules large and _per- 
sistent. oung plant has alternate, willow-like, lake aaned; 
Soryeiied. peliuaid ates closely resembling the serratus var. of 
tags ane I propose the name Jacksoni for it as a variety of P. 
ch oannee saechitiy 
oe e-specimen sent to the Record 
. ‘club ( biow in ‘Herb. I Brite Mus fon) fora Mr. Jackson’s plant to 
