460 PROCEEDINGS OF THE AMERICAN ACADEMY. 



brunnescens they are distinctly beaked, of more membranous texture, and 

 usually with serrate margins. 



The commonest form of Corex canescens in North America is the 

 plant mentioned without name by Francis Boott and figured by him 

 in his Illustrations, IV. table 496. This unique American form, which in 

 essential characters is like true C. canescens, differs in its elongated in- 

 florescence, 5 to 15 dm. long, at least the lower spikelets very remote. 

 The plant seems to have been generally treated by American authors as 

 typical C. canescens, and no published name is available for it. 



The following synopsis presents the characters and ranges of the 

 northeastern Hyparrhenae as now understood by the writer. In its 

 preparation he has studied the material in the Gray Herbarium and the 

 herbarium of the New England Botanical Club ; as well as the hundreds 

 of sheets in the herbarium of the Geological Survey Department of 

 Canada, kindly placed at his disposal by Mr. James M. Macoun ; those of 

 the Olney Herbarium of Brown University, made accessible to him by Mr. 

 J. Franklin Collins; and a series from the Fairbanks Museum at St. Johns- 

 bury, Vermont, rich in forms of the scoparia group, specially accumulated 

 by the director, Dr. T. E. Ilazen, for detailed study, and then generously 

 forwarded to the writer. He has also been greatly assisted by the use 

 of material from the private herbaria of the Honorable J. R. Churchill ; 

 President Ezra Brainerd ; Doctors C. B. Graves, J. V. Ilaberer, G. G. 

 Kennedy, and C. W. Swan ; and Messrs. Luman Andrews, C. H. Bissell, 

 Walter Deane, E. L. Rand, W. P. Rich, and E. F. Williams. The 

 identification of dubious species of Willdenow and of Schkuhr has been 

 facilitated by the cooperation of Dr. J. M. Greenman while at the Royal 

 Botanical Museum in Berlin, and by Prof. Carl Mez of the University 

 of Halle ; and authentic material of the late Dr. E. C. Howe's Car ex 

 seorsa has been generously furnished by Prof. C. H. Peck. 



HYPARRHENAE, Fries. Staminate flowers scattered or at the 

 base of the uniform spikelets (only in exceptional individuals and in the 

 often dioecious C. gynocrates and C. exilis the entire spikelet staminate). 



Key to Species. 1 



* Perigynia with thin or winged margins. 

 •4- Perigynia ascending, the tips only sometimes wide-spreading or recurved, 

 not spongy at base, the margins winged at least toward the beak. 



1 The perigynial characters are here based on study of mature plants. In gen- 

 eral the perigynia at the tip of the spikelet are less characteristic than those nearer 

 the middle ; and, if possible, the latter alone should be used in critical comparisons. 



