8? Rhodora [May 
many of the extremes seem to pass by transitional specimens to one or 
another of the other varieties. A prolonged study of the group as 
represented both in America and in the Old World has failed to bring 
out such beautifully clear lines of demarcation as are now known to 
separate the species of the Juncus tenuis group (until recently aggre- 
gated as J. tenuis), so that the writers, at present, do not feel justified 
in treating them as more than geographic varieties of a cosmopolitan 
type. T 
In any critical study of the group which passes under the general 
name of Juncus effusus the first requisite, of course, is the identification 
of the typical form of J. effusus L. This seems nearly impossible 
except by cireumstantial evidence, since the original treatment of the 
species was so very uncritical. ‘The typical form, however, must have 
been from Europe, so it has seemed desirable to determine first whether 
we have in America anything that will match with sufficient closeness 
anything in Europe. In the Gray Herbarium there are many sheets 
of J. effusus from various parts of Europe, but after prolonged study 
we have reluctantly come to the conclusion that there is nothing in 
America closely similar to those European sheets which agree best 
with the descriptions given by recent European authors of typical 
J. effusus. This European material all agrees in having very small 
flowers with a comparatively soft perianth after the manner of var. 
compactus; and it seems probable that the var. compactus is really 
only J. effusus with a more condensed inflorescence than the most 
typical form of the species. ‘The basal sheaths in the European plants 
may be pale or dark (var. atratus Aschers. & Graebner, Syn. ii. pt. 2, 
443, 1904). In America the only forms (except var. compactus) 
which might possibly be considered as identical with the European J. 
effusus are those here treated as var. solutus and var. decipiens. The 
former, var. solutus, though having a similar stature and pale sheaths, 
nevertheless differs from the European in the more rigid and ap- 
pressed perianth and very diffuse inflorescence which is even larger 
than that of the hollow-stemmed European var. fistulosus Buch. 
'The var. decipiens, in the size of the flowers, texture of the perianth, 
and size of the inflorescence agrees well with the European material, 
but in the slender wiry culms with very dark reddish-brown sheaths 
is unlike any material we have seen from Europe, but on the other hand 
matches almost exactly all the material in the Gray Herbarium from 
eastern Asia. 
