T. Holm — Studies in the Cyperacece. 217 



might append to these some observations upon the internal 

 structure of the species in order to illustrate the section as 

 completely as possible. 



The root. 



Haviug examined roots of a number of specimens from 

 widely separated localities and of different age and develop- 

 ment, we have, nevertheless, failed to detect any anatomical 

 character of importance by which the " formm hebetatce " 

 might be distinguished from each other or from their allies 

 among the " centrales " and " desciscentes" Like most of the 

 other Carices examined, the root possesses a hypoderm of a 

 single layer inside the epidermis, and this tissue is thinwalled 

 in all the species of Astrostachyce. The cortex is differen- 

 tiated into two zones, an outer and an inner, of which the 

 former is distinctly thickwalled in contrast to the inner, which 

 shows the usual tangential collapsing. The endodermis is more 

 or less thickened, but as it seems constantly as an U-endo- 

 dermis ; it is very heavily thickened in G. echinata, less so in 

 the other species. In C. gynocrates the endodermis showed 

 only a very slight thickening of the inner cell- wall in speci- 

 mens from arctic Greenland, while others from Canada, Alaska 

 and Wyoming showed a very pronounced thickening of both 

 the inner and radial cell-walls. The pericambium is usually 

 thinwalled or moderately thickened as in C. exilis, C. echinata, 

 O. sterilis and C. Imviculmis ; it was found to be interrupted 

 by all the proto-hadrome vessels, without exception, in all the 

 species of the Astrostachyce The leptome and hadrome is 

 well developed, and the central portion of the root is occupied 

 by conjunctive tissue, which is quite thickwalled in all the 

 species, especially in C. exilis, C. echinata and C. sterilis. 



In considering the development of the outer cortex, the 

 endodermis and the conjunctive tissue, the roots of these 

 species seem well supported in mechanical respect, and equally 

 well in species from bogs or woodlands. 



The rhizome. 



The rhizome of the "formae hebetatse" is stoloniferous in 

 C. dioeca, C. gynocrates and C. parallela, but cespitose in the 

 other species. Epidermis is mostly thickwalled, and a hypo- 

 derm of a single stratum is noticeable inside the epidermis. 

 The cortical parenchyma is, also here, differentiated into two 

 zones, of which the outer is quite thickwalled. The endo- 

 dermis shows the same manner of thickening as observed in 

 the roots, and is especially thickwalled in 0. parallela and C. 

 Davalliana. The stereome occurs in C. parallela as a peri- 

 pheral band of small isolated groups near epidermis, but is in the 



