T. Holm — Studies in the Cyperacece. 43 



Geyeri the cortical parenchyma shows about eight thick-walled 

 strata near the periphery, while the inner ones are very thin- 

 walled ; otherwise the structure of the stereome, the endo- 

 dermis, etc., is like that of G. Willdenowii and G. Steudelii. 



The stem. 



The above-ground stem is somewhat rough from prickle-like 

 projections from the epidermis and triangular in G. Willde- 

 nowii, G. Steudelii and G. JBackii. However, when we 

 examine the structure closer, it is readily seen that the outline 

 is so sharply triangular that the term "three-winged" may be 

 well applicable to these species. The cuticle is smooth and 

 thin in all three species ; the epidermis shows a distinct thick- 

 ening of the outer walls, with the exception of the cone-cells ; 

 stomata are quite abundant. The cortical parenchyma is very 

 poorly developed in G. Steudelii, consisting only of one stra- 

 tum short, roundish cells, which border on wide lacunes. In 

 G Willdenowii this same parenchyma is better developed and 

 shows several layers with relatively narrow lacunes ; in G. 

 Backii there are distinct palisades, but the lacunes are very 

 wide in this. The stereome is thickwallecl in G. Willdenowii 

 and G. -Backii, but not so in the third species ; it accompanies 

 the mestome-bundles either as hypodermal groups or separated 

 from the epidermis by the cortex ; it is, also, present on the 

 hadrome side of the mestome-bundles ; it reaches its highest 

 development in the three wings, where it, furthermore, occurs 

 as isolated groups, not being in contact with any mestome- 

 bundles. These, the mestome-bundles, are very regularly 

 arranged in one band near the periphery and represent larger 

 oval in alternation with smaller, almost orbicular bundles, 

 when viewed in transverse sections; the parenchyma-sheath is. 

 thinwalled. and the inestome-sbeath shows its inner cell-walls 

 to be distinctly thickened. A thinwalled pith occupies the 

 center of the stem ; it is hollow in G. JBackii, solid in the 

 other species. 



In G. wdipostyla the stem is triangular, but without being 

 winged, and the outer cell-walls of epidermis are more heavily 

 thickened than in the former species ; the cortex is more open, 

 there being very distinct intercellular spaces besides lacunes of 

 quite considerable width. The stereome is thickwalled, but 

 does not occur separate from the mestome-bundles, which are 

 here represented in two concentric bands, instead of but one 

 as in the former species; the mestome-sheath shows the cells to 

 be thickened all around. A partly hollow pith occupies the 

 center of the stem. In G. Geyeri and C. multicaulis the 

 stem is longer than in the former species and shows, also, a 



