438 BOTANICAL GAZETTE [DECEMBER 
(fig. 6, C) or as a homogeneous tissue of roundish cells (in cross- 
section). The former structure is the most frequent, and especially 
well represented in Poa rupicola, P. Lettermanni (fig. 6), and Agrostis 
canina; the latter structure was observed in Agrostis varians, 
Poa flexuosa, Agropyrum, Calamagrostis, Deschampsia, and Festuca. 
We will finally consider the structure of the cuticle and epidermis. 
The cuticle was observed to be smooth and quite thick in all the 
species, even in the densely hairy Trisetum. The epidermis is 
scabrous in Calamagrostis, hairy in Trisetum, but glabrous in the 
others. Some slight variation in the structure of the cell walls was 
noticed; the outer wall, for instance, is quite thick as compared with 
the inner and the radial, and this structure seems to be the most fre- 
quent. But in Agrostis canina, Poa rupicola, Phleum alpinum, and 
Agropyrum violaceum all the cell walls of epidermis were equally 
and quite heavily thickened. : 
A very firm structure is thus exhibited by the culms of our alpine 
Gramineae, so far as concerns the mechanical tissue and the dense 
cortical parenchyma covered by a thick-walled epidermis. It 3 
also interesting to notice that the cortex generally contains much 
chlorophyll, and that the cells are developed as typical palisades, thus 
being able to perform the function of the chlorenchyma in the leaves. 
The modifications in structure in the culms depend mostly upon the 
distribution of the stereome, and upon the mestome strands (their 
relative size, their mechanical support, and their disposition in one 
or two concentric bands). The pith, on the other hand, shout © 
deviation from the most common structure known in this family; 
it was constantly found to be thin-walled and broken in the center, 
and with no deposits of starch. 
The leaves : 
In the leaves the epidermis and chlorenchyma offer some saanr’ 
tions of importance, and much more so than the stereome, at least 9 
the alpine species. However, the structure is very uniform, ee 
not exhibit any such prominent epharmonic characters as are uae 
known from species of the lowlands, the plains, and the pra” 
In the alpine species the leaf structure is very firm throughout; a 
are no wide intercellular spaces in the chlorenchyma, and no W 
