‘IRbodora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB : 
Vol. 20. May, 1918. No. 233. 
SOME SPECIES AND VARIETIES OF ELYMUS IN EASTERN 
NORTH AMERICA. 
K. M. WIEGAND. 
Tue genus Elymus has long been a problem to students of grasses. 
The older treatments were wholly inadequate, since several of the 
common species were formerly unrecognized. During recent years 
Scribner and others have described several additional species from 
eastern North America, but no comprehensive treatment of the genus 
was given by these writers. In 1908 Hitchcock contributed the article 
on Elymus to the seventh edition of Gray’s Manual, but this treatment 
seems not to have cleared the situation to any appreciable extent; 
and the same statement may be made in reference to the treatment of 
the genus by Nash in the second edition of Britton and Brown’s Hlus- 
trated Flora in 1913. During the course of studies upon the plants 
of central New York, the writer became interested in Elymus. The 
present article is the result of this study. It was begun in the herba- 
rium of the College of Agriculture at Cornell University; but later, 
through the courtesy of those in charge of the Gray Herbarium, the 
work was continued and completed at that institution. The revision 
is herewith presented with the hope that it may contribute toward a 
clearer understanding of the genus. 
In many instances it will be noted that the characters used in the 
key are not those ordinarily employed to separate species of Elymus. 
To the writer these here used seem more essential, and seem to separate 
the species more naturally. During the study a very great many 
measurements were made of all parts of the plant, and a surprising 
eonstancy in size, within certain limits was noted in each species and 
