T. Holm — Studies in the Cyperacece. 443 



smooth with no furrows, and consists usually of smaller cells 

 than that of the upper, and is frequently developed into uni- 

 cellular hairs or very .minute spines, which are directed 

 upwards. The stomata are restricted to the lower epidermis, 

 where they form longitudinal rows outside the mesophyll 

 between the mestome- bundles. Characteristic of the stomata 

 is the deep and somewhat narrow air-chamber, which we have 

 noticed in most of our species with the exception of F. cas- 

 tanea, where it is shallow and wide. The guard-cells are pro- 

 jecting in F. autumnalis, F.laxa, F. puberula, F. spadicea 

 and F complanata, but not in the other species ; they are 

 extremely thick-walled in F. castanea. 



Similar to all' the other Cyperacece, examined so far, silicious 

 cones are observable in the epidermis-cells that cover the 

 stereome. As regards mechanical support most of our species 

 possess a well-developed stereome, the location of which can be 

 seen on the sections, figured above. It accompanies the larger 

 mestome-bundles as hypodermal groups on the lower surface of 

 the blade, while on the upper it is restricted to the margin. A 

 few thin-walled stereome-cells may be found above some of the 

 largest mestome-bundles, but separated from these by meso- 

 phyll. Although the stereome does not form any sheaths 

 around the mestome-bundles, it nevertheless renders a strong 

 support to the leaf by its very thick-walled cells, and is alto- 

 gether very well represented in our species of Fimbristylis, 

 with the only exception of F. autumnalis and F. laxa, in 

 which it is relatively thin-walled. 



The chlorophyll-bearing tissue, the mesophyll, occupies only 

 a small part of the leaf-blade, since it is generally traversed by 

 a number of mestome-bundles, which are especially large in 

 the narrow-leaved species, such as F. capillaris, F. Warei, etc. 

 It forms a homogeneous tissue on both faces of the leaf, and 

 the cells are true palisades, arranged radially around the 

 mestome-bundles. Furthermore this tissue is very compact in 

 our species excepting in F. laxa, of which some specimens 

 from Florida showed wide lacunes ; and F castanea, in which 

 the palisade-cells are almost star-shaped, leaving numerous and 

 quite large intercellular spaces. Tannin was observed to be 

 very plentiful in this tissue, especially in F. spadicea, F. 

 puberula and F. thermalis. 



Considering the mestome-bundles, these are all arranged in 

 a single plane in the leaves of Fimbristylis ; they vary in pro- 

 portion to size and outline, the larger being more or less oval, 

 the smaller constantly orbicular. They are imbedded in the 

 mesophyll, and are, as we have seen above, in no connection 

 with the stereome, hence they are " pure" mestome-bundles. 



