589 
Galium trifidum and its North American Allies. 
By KARL M. WIEGAND. 
For many years this group of plants has seemed to the writer 
one of the most perplexing with which the American botanist has 
to deal. Two individuals would appear so distinct as to be at 
once taken for distinct species, but all text-books referred both to 
the one name G. sifidum, “an exceedingly variable species.” 
Distrust was aroused more and more as to the correctness of 
this treatment of Gadium since experience shows that species in 
other genera very rarely exhibit such a wide range of indefinite 
variation. The complexity of many aggregate species is found to 
be due to the confusion of distinct but closely related sub-groups, 
and not to one single unbroken and highly variable species. To 
distinguish and designate these sub-groups when they exist is 
unquestionably a benefit to our conception of the group as a 
whole, and it was on this account largely that the study was 
undertaken which led to the present paper. 
It was soon apparent that this was the principal cause of the 
confusion in the case of Galium. G. trifidum L. which was desig- 
nated as the “highly variable” species, although its components 
still exhibit a remarkable amount of variability, readily allows of 
Segregation into a number of well defined species and as many 
good varieties which are as distinct as most of the other North 
Americal representatives of this genus. The following discussion 
is an attempt to bring the “ #fidum” group into a more orderly 
condition. 
There has always been considerable difference of opinion as to 
the taxonomic value of different characters in the genus Galium, 
We shall concern ourselves merely with those used to separate the 
species of the trifidum group. The conception of a species here 
as elsewhere, of course necessarily differs with the individual. It 
will be readily seen in the synopsis given below that the greatest 
importance is placed upon a so-called « internal character,” namely 
the form that the seed presents in cross-section. Practically speak- 
ing this means the cross-section of the endosperm and does not 
include the carpellary coat. This character so far as known to the 
