44 T. Holm — Studies in the Cyperacece. 



much more solid structure ; the cortex constitutes a compact 

 palisade-tissue with relatively small lacunes, especially in the 

 latter species. The stereome occurs in larger groups and is 

 very thickwalled, but invariably accompanying the mestome- 

 bundles ; the sharp angles of the pentagonal stem of G. Geyeri 

 have no isolated stereome, but merely cortical parenchyma ; 

 the terete stem of the other species possesses a larger number 

 of mestome-bundles and, consequently, it contains, also, more 

 stereome. The mestome-bundles constitute a single band and 

 the mestome-sheath is very heavily thickened. The solid pith 

 is thickwalled in C. Geyeri, but thin walled in the other. 



The leaf 



is narrow, but flat in G. Willdenoivii and G. Steudelii, rela- 

 tively broad in G. Backii. The cuticle is thin and smooth in 

 the former species, but quite thick in the latter. Epidermis 

 exhibits several modifications; it is perfectly glabrous and 

 smooth on the upper face in G. Steudelii and G. Willdenowii, 

 and is differentiated into a row of bulliform cells just above 

 the midrib ; above the stereome the epidermis, viewed " en 

 face " consists of narrower and shorter cells than those which 

 cover the mesophyll. If we examine the lower surface of the 

 leaf we notice a corresponding structure, but there are no 

 bulliform cells, and stomata are observable outside the meso- 

 phyll ; these are but slightly projecting and possess a wide but 

 shallow air-chamber. If we consider the leaf of these species 

 in cross-sections, we notice that the outer wall of epidermis is 

 slightly thickened and somewhat projecting in the shape of 

 very minute papillae on either side of the midrib, but only on 

 the lower surface. In Garex Backii the epidermis-cells are 

 very short outside the stereome, much shorter than we observed 

 in the former two species ; their outer wall is very thick and 

 we find here small wart-like projections from the epidermis, 

 which form several rows on each side of the bulliform-cells, 

 besides that there are four such projections around each stoma. 

 The mesophyll is differentiated into a distinct palisade-tissue 

 on the upper face of the leaf of G. Steudelii and G. Willde- 

 noivii, while it consists of roundish cells with large intercellu- 

 lar spaces on the lower face, almost . as a typical pneumatic 

 tissue ; large lacunes traverse the mesophyll in both species. 

 In G. Backii, on the other hand, the mesophyll is nearly homo- 

 geneous throughout the blade, very open and without palisade- 

 cells. The stereome is thickwalled in G. Willdenowii and 

 G. Steudelii, but quite thin walled in G. Backii. It accom- 

 panies the mestome-bundles as hypodermal groups on either 

 face, at least in the larger bundles, and there is, also, an iso- 



