Rhodora 
JOURNAL OF 
THE NEW ENGLAND BOTANICAL CLUB 
Voc mE us 
= 
May, 1910. — No. 137. 
THE NORTH AMERICAN VARIATIONS OF JUNCUS 
EFFUSUS. 
M. L. FERNALD and K. M. WIEGAND. 
PERHAPS no species of the genus Juncus is more familiar than is 
Juncus effusus L., largely because of its wide distribution in temperate 
regions of both the Northern and Southern Hemispheres. Like most 
species of almost cosmopolitan range, however, it has developed cer- 
tain pronounced geographic variations, many of which have been 
described either as varieties or as distinct species, but few of which 
have been recognized by American students of the genus. During 
the past summer, while botanizing extensively in eastern Maine and 
adjacent New Brunswick, the writers became convinced, from their 
field observations, that as represented in that district Juncus effusus 
consisted of several well-marked varieties or possibly species. Subse- 
quent study of all the material in the Gray Herbarium, the herbaria 
of the New England Botanical Club, the Geological Survey of Canada, 
the Philadelphia Academy of Natural Sciences, and the Philadelphia 
Botanical Club, and the private collections of Messrs. H. H. Bartlett, 
Walter Deane, G. G. Kennedy, and other members of the New Eng- 
land Botanical Club, has shown that not only are there several good 
varieties in eastern America, but that in the main the plants of the 
Pacific Slope represent a different series of variations. In all these 
plants the general habit is very similar and the perianths, capsules, 
and seeds are in their more important characters essentially the same. 
In fact, though showing marked varietal tendencies in the size and 
texture of the culms; the texture, size, and color of the basal sheaths; 
the size and branching of the inflorescence; the texture, length, and 
color of the perianth-segments; and the color and size of the capsules; 
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