T. Holm — Studies in the Cyperacece. 41 



cation of Drejer, where the species are arranged not in 

 accordance with such artificial characters as are applied for the 

 separation of mono-, homo- and heterostachyos, or of di- and 

 tri-stigmaticce, but in accordance with purely natural affinities. 

 It becomes, thus, evident that each of Drejer's " greges " or 

 sections, as we may call them, is really an aggregate of a num- 

 ber of apparently very diverse forms, beginning with the 

 "forme® hebetatce" and passing gradually over into "formes 

 centrales" from which again a number of allied species, but 

 somewhat differently developed, extend towards the limits of 

 the section as "formce desciscentesP An anatomical investiga- 

 tion of some of these parallel forms, the " hebetate® " for 

 instance, will no doubt reveal certain analogies with the corre- 

 sponding "formce hebetatw" of other sections, while the cen- 

 tral types may be very distinct. In this way the anatomical 

 characters become obscure, and it will be necessary to make 

 many comparisons between the various forms of each section, 

 before we shall know where to draw the distinction between 

 the characters of the section "as its own," and those, which 

 may be regarded as inherited from old types through its 

 u formce hebetatce." Our anatomical study of Carex Willde- 

 nowii and its allies must, therefore, necessarily be incomplete, 

 but may, perhaps, be useful in further research, at least as a 

 contribution to comparative studies of other species of the 

 genus. We shall not, however, confine ourselves to these 

 species, but we will compare their structure with that of O. 

 eedipostyla, G. Geyeri and G. midticaulis. The structure of 

 utri cuius is, no doubt, the most important, yet, as will be 

 shown, some interesting characters may, also, be obtained from 

 the root, the stem and the leaves. In regard to the localities, 

 from where our material was gathered, we might state that 

 both G. Willdenowii and G. Steudelii were collected in the 

 woods near Brookland, D. C. ; that the former especially pre- 

 fers shaded places in rich woods, while the latter inhabits drier 

 ground in thickets or open woods ; G. Backii was received 

 from Mr. James M. Macoun in Ottawa, as collected on dry, 

 grassy and rocky places in open woods and thickets near 

 Ottawa ; G. Geyeri from the Rocky Mountains in Montana 

 and British Columbia, in somewhat damp ground ; C. midti- 

 caulis from Wyoming; C. cediposlyla from thickets near Mont- 

 pellier in southern France. 



The root. 



The epidermis and hypoderm show a uniform structure in all 

 three species : Carex Willdenowii, C. Steudelii and G. Backii. 

 The cortex is thin-walled throughout in the last species, but 



