1916] Fernald & Weatherby,— Puccinellia 3 
In attempting to determine the large collections of Puccinellia 
which have accumulated at the Gray Herbarium, especially from the 
shores of the Gulf of St. Lawrence, the writers have found it impossible 
to place many of the plants with the species commonly recognized 
as occurring in eastern America. It has consequently been necessary, 
in order to make the identifications of these plants as certain as pos- 
sible, to study with some thoroughness all the species to which they 
are nearly related or with which they may be conspecific. This 
study has been greatly facilitated by the loan, through Dr. J. M. 
Macoun, of the large northern collections of the Geological Survey of 
Canada, by Dr. M. O. Malte of his private collections, and, through 
Mr. Bayard Long, of the representation in the herbarium of the 
Academy of Natural Sciences of Philadelphia; and we here express our 
appreciation of the opportunity to examine this most important 
material which, with the collections of the Gray Herbarium and of 
the New England Botanical Club, has been the chief basis of our work. 
It quickly became apparent that much of the difficulty heretofore 
experienced in efforts to differentiate the species of Puccinellia has 
arisen through attempts to divide the plants too generally upon the 
habit of the inflorescence. Many species which in full maturity have 
the branches of the panicle widely divergent, in the young condition 
have close inflorescences with ascending or even appressed branches; 
so that attempts to use this character often lead to confusion. In 
searching for more fundamental characters which should be constant 
in all the material of seemingly identical plants many fruitless experi- 
ments were made; but finally the results resolved themselves into a 
series of differential points which seem to be reasonably definite and 
to divide the complex of material upon natural and geographically 
consistent lines. These characters have been tested through a pro- 
longed study, which has occupied portions of three years, and although 
here indicated chiefly for the species which occur in eastern North 
America (south of Hudson Straits) they will prove important, we are 
sure, in the differentiation of the species of northwestern North 
America, Eurasia and the Arctic, in each of which areas there are 
several species not here discussed. 
In the region specially covered by this paper (the area south of 
Hudson Straits) there are eleven well defined species of Puccinellia, 
each, as already implied, occupying a consistent geographic area. 
In two species, P. maritima and P. phryganodes, the anther is 1.5- 
