282 T. Holm — Studies in the Cyperaceae. 



stem, the stomata are surrounded by mostly four papillae, 

 which, however, are quite short and not bent over the stoma, 

 thus this is almost free as in the other species. This structure 

 of the subsidiary cells with their papillae in C.firnbriata has 

 already been described by Schwendener in his paper on the 

 stomata of the Graminece. and Cyperacem* 



The mesophyll is either represented as a homogeneous tissue 

 throughout the leaf, as in G. cireinaia and C. lejocarpa, or it 

 is differentiated into a more or less distinct palisade-tissue on 

 the upper face and a more open, pneumatic on the lower, as in 

 C.ferruginea; in the other species the palisades are short and 

 not so regular, but appear nevertheless to be placed vertically 

 on the blade, with the exception of C. ablata, in which the 

 palisade-cells show a tendency to radiate towards the center of 

 the mestome-bundles. Lacunes were observed in all the 

 species, one between each two mestome-bundles, and they were 

 especially wide in C. circinata, C. lejocarpa, C. misandra and 

 C. hispidula. The stereome occurs as in the stem on both 

 faces of the mestome-bundles and as hypodermal in the larger 

 of these ; it is, moreover, to be observed as a small, isolated 

 group in each of the two leaf-margins. It is very thick-walled 

 in C. sempervirens and C. ferruginea, moderately so in the 

 other species ; it is rather weakly developed in C. ablata. 



The mestome-bundles lie in one plane, and the midrib is 

 generally somewhat larger than the others and more promi- 

 nent. We find in the leaf as in the stem two forms of these 

 bundles, larger and smaller, which show the same alternation 

 in regard to their arrangement and the same structure as we 

 have described under the stem. 



* The position of the stomata in Garex, whether these are free and exposed or 

 sunk below the surrounding epidermis and sometimes partly covered by papillas, 

 does not seem to be of any importance in regard to thfe classification of these 

 species. On the contrary, Mazel has shown that species from the various sec- 

 tions of Carex may exhibit the same structure and position of stomata, and there 

 does not appear to be 'any relation between stomata, being free or not, and the 

 local environment, climate and soil. This author has shown, for instance, that 

 C. Davalliana, G. Pseudocyperus and G. hirta, all from swamps, possess super- 

 ficial stomata. while these are sunk in G. paniculata, G. vulgaris, C. paludosa, 

 etc., from similar wet localities. In species which inhabit drier stations, woods 

 and hills, a similar variation exists ; thus the stomata are superficial and perfectly 

 free in, for instance, C. divulsa, C. brizoides, G. prcecox, C. sylvatica, etc., but not so 

 in G. maxima, C. glauea, etc. A still more peculiar case may be illustrated by C. 

 misandra, which we have examined from very different and remote localities: 

 arctic and alpine regions of America aud Europe, still maintaining the same 

 structure and free position of the stomata, while in C. capitata, which we found 

 growing almost side by side with this species, the stomata are protected by long 

 and almost ramified papillae. 



It does seem as if the position of the stomata is not always an indication of the 

 conditions of the surroundings under which the plants live, and it is, no doubt, 

 one of the many inherited characters which are explainable only in a few species 

 to which the natural surroundings are unchanged. 



