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 Engehnanni (Figs. 30 to 40), which has been treated, now 

 as a variety of E. ohtusa (ovata), now as a distinct species, is generally 

 given specific recognition. Resembling E. ohtusa in habit, it is fairly 

 characterized by its narrower elongated head, by its more compressed 

 tubercle, and by its shorter bristles. It requires no detailed discussion 

 here. 



From these recent studies it seems that the American Eleocharis ohtusa 

 of Schultes is really distinct from the European E. ovata with which it 

 has been united, but that, although rare with us in its typical form, the 

 true E. ovata is represented in northeastern America principally by the 

 little known Prussian (Silesian) var. Heiiseri. And many annual plants, 

 it seems, which have been associated with these species in our herbaria, 

 though in some cases as closely related to E. Engelmanni, cannot be 

 satisfactorily identified with either species. Nor are these plants more 

 readily placed with the other species, E. intermedia, E. palustris, and E. 

 olivacea, with which they have sometinies been associated. On this 

 account they are here proposed, some as distinct specific types, others as 

 extreme varieties of older species ; and with the hope of diminishing the 

 confusion which has so long existed among them, the following synopsis 

 has been prepared of all the annual American forms (excluding the very 

 distinct E. 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- 

 posal. 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. W. Swan, Rev. E. C. Smith, and Messrs. Walter Deaue, E. L. 

 Rand, W. P. Rich, and E. F. Williams. 



