NOTES ON POTAMOGETON 147 
62 (1901), with a plate (photo-process). The figure looks much 
like a polygonifolius form, but the enlarged leaf-structure quite 
denies this, and from this and the figure (outline) of the fruit I 
should think its place is near P. alpinus Balb. = rufescens Schrad. 
1 > 
eaves; from both in the straighter, more upright growth, 
especially the leaves; less diffuse than in alpinus, more so than in 
mMericanus 
Gathered by the Rev. E. J. Hill in railway ditches, Stoney 
Island, Chicago, Ill., U.S.A., in Aug.—Sept., 1900, and Aug. 1901. 
This is not the same as P. yoni Morong, Mon. N. Am. Naiad., 
t. 82, p. 22, 1893, which, notwithstanding a good series from the 
author, I have some difficulty in separating from P. americanus 
nearly sessile, or tapering to a petiole 0-5-1 cm. Stipules 2-2:5 cm. 
long, shining, acuminate. Peduncles 4-5 cm. long, slightly 
. 
* 
It was abundant in the ditch w 
+ PU r. psEupo-RutiLUs Ar. Benn. in Journ. Bot. 
1901, p. 201. On the receipt of further specimens of this plant 
from the Rev. E. J. Hill, gathered in 1901, and on examining the 
forms of pusillus from all parts of the world, I have come to the 
Conclusion that this must be held a species. It is the most rigid- 
leaved of the genus known to me (P. rigidus Wolfg. R. et S. Mant. 
mM 2 
