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FERNALD, — ELEOCHARIS OVATA. 491 
For this reason, and in view of the slight though apparently constant 
habital and structural differences, it seems hardly justifiable to identify 
the Sierra Nevada and northern plant with the species of the central 
and southern prairie States. 
Eleocharis Engelmanni (Figs. 30 to 40), which has been treated, now 
a0 variety of EH. obtusa (ovata), now as a distinct species, is generally 
Siven specific recognition. Resembling #. obtusa in habit, it is fairly 
characterized by its narrower elongated head, by its more compressed 
ean and by its shorter bristles. It requires no detailed discussion 
ere. 
From these recent studies it seems that the American Eleocharis obtusa 
of Schultes is really distinct from the European 2. ovata with which it 
has been united, but that, although rare with us in its typical form, the 
true Z. ovata is represented in northeastern America principally by the 
little known Prussian (Silesian) var. Hewser?. And many annual plants, 
It seems, which have been associated with these species in our herbaria, 
though in some cases as closely related to #. Engelmanni, cannot be 
satisfactorily identified with either species. Nor are these plants more 
teadily placed with the other species, E. intermedia, E. palustris, and £. 
olivacea, with which they have sometimes been associated. On this 
account they are here proposed, some as distinct specific types, others as 
*xtreme varieties of older species; and with the hope of diminishing the 
confusion which has so long existed among them, the following synopsis 
as been prepared of all the annual American forms (excluding the very 
distinct Z. intermedia) here discussed. : 
In the preparation of this paper, besides the extensive collection of 
Eleocharis in the Gray Herbarium, and those in the Herbaria of the 
United States National Museum, the Canadian Geological Survey De- 
partment, Brown University, and the New England Botanical Club, the 
valuable sheets in many private herbaria have been placed at my dis- 
To Messers. F. V. Coville, James M. Macoun, and J. Franklin 
Collins I am indebted for the use of material in their charge, and to the 
following gentlemen, whose private collections have largely supplemented 
the representation of species exhibited in the public Herbaria consulted : 
— President Ezra Brainerd, Judge J. R. Churchill, Drs. G. G. Kennedy 
and C. Ww. Swan, Rev. E. C. Smith, and Messrs. Walter Deane, E. L. 
Rand, W. P, Rich, and E. F. Williams. 
