Isoetes riparia Canadensis and Isoetes Dodgei 
By A. A. Eaton 
For a period of nearly seventy years, and from widely sepa- 
rated localities, an /soetes has been collected and variously referred 
by authors, but always with hesitation and doubt, until 1898, when 
it was described in the Fern Bulletin as 7. Dodgei, founded upon 
specimens from Kingston, N. H., and Vancouver Island, B. C. 
It is near 7. riparia in many respects, but differs especially in its 
more rigid leaves, usually with four bast-bundles, its light-spotted 
sporangium, and the rather jagged, isolated crests of the gyno- 
spores. Noting Dr. Engelmann’s rather vague description of 7. 
riparia Canadensis in his monograph, specimens of 7. Dodgei were 
sent to be compared with that variety, and were pronounced dis- 
tinct. Through the kindness of Dr. Trelease I have since had an 
Opportunity to examine all of Dr. Engelmann’s material of this. 
genus, and have established with little room for doubt that not 
only are £ riparia Canadensis and I, Dodgei identical, but that 
nearly all of Engelmann’s so-called /. riparia from New England, 
a part of that from Pennsylvania, and even some specimens re- 
ferred to /. Engelmanni, are that species also. 
The cause of confusion doubtless lies in the fact that all of 
Engelmann’s material of this is more or less immature and frag- 
mentary. There appears to be no type-material in his herbarium, 
for in ‘* Notes and Sketches,” 59: 90, he states that all his speci- 
mens, which were poor, were sent to Braun, who said they 
were “probably of a new species between /. /acustris and J. ri- 
Paria.” This was from Canada, the place, date and collector not 
given. We may conjecture, however, that it came from Crow River, 
collected by Macoun. Engelmann cites two localities for the va- 
riety: Cornish, Maine, Chickering, and Crow River, Canada, Ma~ 
coun. Of the latter he has three plants, all told, of 6-10 leaves, 
7-5-I0 cm. high. They grew under water and have a starved 
appearance, According to the label it was found “in rather swift- 
running water just above the dam at Marmora iron works,” etc., J, 
Macoun, July 18, 1864. The submersed position and early date 
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