NOTES ON POTAMOGETON 149 
the conditions are unfavourable where there is the means of multi- 
plying so fully supplied.’’ 
- AmPLIFoLIUS Tuckerm. In some valuable notes on the 
variation of species of Potamogeton,* Mr. Hill remarks that in 
les. But so 
far as one can judge from a very fine series of amplifolius (including 
specimens from Tuckerman) from over its whole area o istribu- 
tion, the submerged leaves would seem to keep them sufficiently 
apart, exclusive of the other characters. These investigations in 
situ are very valuable, but difficult, unless one has unlimited time. 
If correct, the notes on “ P. lucens” point to a condition of growth 
in that species that has never been observed before, and would 
need direct cultivation to confirm. 
By the kindness of Professor Macoun and his son, I have a set 
of the Potamogetons gathered last year in the Canadian Dominion; 
among them is one gathered by Professor Macoun, at Little Eagle 
Harbour, Lake Huron, Ontario. : 
It consists of only young specimens, without flower or fruit; 
species, as there is no other American species with the young 
growth as this. In zosterifolius, acutifolius, obtusifolius, &c., the 
young plants always have broader leaves than those produced after- 
these Canadian, and the U.S.A. specimens makes me doubt its 
to be referred to my P. Preussii (Fl. Trop. Afr. viii. p. : 
or be described as a new species; or that the Chinese specimens 
may be Hillii, but not the others. But more material is needed. 
(To be continued.) 
ak De aD eae 
* Bot. Gazette, xv. pp. 147-149, 326-327 (1890). 
