NOTES ON POTAMOGETON 249 
open, but there is not the slightest indication that any of the 
stigmas are fertilized. 
P. alpinus, P. pensylvanicus, and P. americanus all grow _to- 
gees in Lake Champlain, whence I have specimens from Mr. 
axon. 
x P. curvatus mihi = P. angustifolius Bercht. & Presl. x P. 
lucens L. 1. Bar Lake, Manistee, Mich., U.S.A.; 2. Dutcher’s 
Bridge, Housatanie River, Conn., U.S.A. ; Dr. Robbins ex Morong. 
These puzzling specimens were named P. gramineus? by Dr. 
Robbins ; Dr. Morong suggested a form of lucens, and T a form of 
uae t ‘ 
green ; many shining, small (2-5 cm. x 2 cm.), oval-lanceolate. 
Study in situ is the only way out of the difficulty. 
P. OakeE b 
stitutes the name P. Purshit Tuckerm.in Amer. Journ. Se. (1848), — 
228, observing, “non nomen solum; cum diag.!” Certainly, i 
this applied to Oakesianus, the description is ample enough, 
though subsidiary to another species (i.e. P. Claytonit Tuckerm.), 
but there are difficulties in the way. Pursh (FI. Am. Sept. ii. 120 
barium in my possession, is a plant resembling P. Claytoni, but 
much smaller and more delicate throughout, explaining thus the 
: z ichx. as a synonym of so 
he 
phyllus afterwards added, names as & station ‘‘ Walker’s meadows. 
bridus of Barton’s Comp. Flor. Phil. i. 96 is probably th 
same plant. 
Mr. Fernald, of the Gray Herbarium, writes to me :—* We 
quite 
not believe that his plant was P. Oakesianus, for that is a well- 
marked species which is quite unknown from Virginia aro- 
n Sng bd 
the Vienna herbarium from Virginia, but it does not seem - reac 
Florida, though it occurs in Georgia (Glasgow herbarium !). 
