178 



T. Holm — Studies in the Cyperacece. 



blade are mostly involute, and the blade, which is often very 

 asymmetric, is not carinate. The outline of the blade, when 

 considered in transverse section, is broadly crescent shaped in 

 Z. maeulata with the two halves of unequal size (fig. 3). The 

 same is, also, the case with Z. argentea, but the blade is, in this 

 species, constricted above the midrib and is thinner in propor- 

 tion to its width than in the foregoing species (fig. 4). The 

 blades- of Z. microcephala and Z. sphacelata are less asym- 

 metric and equally thin throughout. The epidermis of the 

 lower surface of the leaf-blade shows the same development as 

 in the stem with a single layer outside the mestome-bundles 

 and two or three rows of cells between these. But on the 

 upper face of the blade in L. argentea and Z. maeulata we 

 find a huge mass of epidermal tissue in layers of considerable 

 width, from five to six, especially towards the margin ; in Z. 

 microcephala and L. sphacelata, on the other hand, there is but 



Fig. 3. Leaf of L. maeulata, transverse section, x 60. 



Fig. 4. Part of leaf of L. argentea, transverse section, x 60. 



one single layer on either face of the blade. In considering 

 Z maeulata and Z. argentea the outer layer of epidermis con- 

 sists of much smaller cells than the inner ones, especially 

 towards the margins, where two or three subepidermal stereome- 

 bundles are located. While the outer epidermis in Z. argentea 

 is developed as bulliform cells above the midrib (n>. 4), where 

 no inner layers are developed, we notice in Z. maeulata, on the 

 same place, a tendency of the outer epidermis to develop in 

 the same way, as bulliform cells, but are separated from the 

 mesophyll by at least two layers of inner epidermis. In the 



