T. Holm — Studies in the Cyperacece. 



179 



two other species the epidermis of the upper face consists of a 

 single layer of cells of almost equal size, but does not seem to 

 develop as groups of bulliform cells, so commonly observed in 

 other genera. The epidermis of the lower surface of the leaf 

 is composed of cells of nearly equal width excepting those 

 which cover the stereome ; these are usually much smaller and 

 contain cones of silica. While the lower surface is very even 

 in L. maculata and L. argentea, we noticed in the two other 

 species distinct furrows between the stereome-bundles like 

 those described above as characteristic of the stem. The 

 stomata are located at the bottom of these furrows, while in 

 L. argentea and L. maculata they are freely exposed, being on 

 a level with the surrounding epidermis. As regards the meso- 

 phyll, this is developed as a sheath around each mestome- 

 bundle, separating these from the stereome of the leptome-side. 

 Thus there exists a strong analogy in structure when we com- 

 pare the bark of the stem with the mesophyll of the leaf, 

 besides this the mestome-bundles in both show an absolutely 

 identical composition. The mestome- and chlorophyll-sheath 

 are developed to the same degree we noticed in the stem, and 

 the mestome-bundles are, also, here represented by two forms : 

 orbicular and oval, when considered in transverse sections 

 (fig. 5). 



Stereome is developed out- 

 side the larger mestome- 

 bundles on the lower surface 

 of the blade, but occurs, also, 

 in one or two isolated groups 

 on the upper face and close 

 to the margin. The margin 

 itself merely consists of the 

 two layers of epidermis with 

 no support of stereomatic 

 tissue. 



The bracts, 



which subtend the spikelets, 

 are membranaceous and con- 

 three sheaths; tannin in a cell drawn tain only one mestome-bundle, 

 with black; Ep. = epidermis of lower -. , -, J . ,-, ^.ini^ A 



surface, x 40o. located in the middle and 



forming a slightly projecting 

 rib on the dorsal face. There is an epidermis of large and 

 thin- walled cells on both faces of the bract, with the exception 

 of the margins, where only one stratum of epidermis is devel- 

 oped. A few of the cells contain tannin, but no chlorophyll. 

 The mestome-bundle is surrounded by a single sheath, a 

 mestome-sheath, the cell-walls of which are but very slightly 



Fig. 5. Leaf of L. maculata, showing 

 i orbicular mestome-bundle with its 



