220 THE JOURNAL OE INDIAN BOTANY. 



angular margin and is supported by angular sfcereome bundles ; other 

 veins are small and are placed in the middle of the mesophyll. 



In the leaf-blade and leaf-sheath of S. maritimus veins are 

 enclosed in an outer ring of stereome and in an inner ring of large 

 colourless polygonal cells. All the veins are vertically transcurrent ; 

 those in the leaf -blade are vertically transcurrent above and below by 

 aqueous cells and those in the leaf-sheath are apposed to lower 

 epidermis and are vertically transcurrent above by aqueous cells. 



The mechanical tissue in G. rotundas (figs. 303, 304) and in 

 C. nivens (fig. 298) is composed of isolated sub-epidermal girders, which 

 are more numerous on the lower surface. On the lower surface the 

 subepidermal girders are found above the veins and on the upper sur- 

 face they occur at regular intervals, being developed more or less above 

 every alternate vein in (J. rotundas. In G. niveus there are some 

 I-girders in association with the larger veins, webs of which are 

 formed by unmixed vascular bundles. In C. conglomcratus and in 

 G. arenarius isolated sub-epidermal girders occur only on the lower 

 surface above the lower veins; and there is a long sub epidermal 

 girder on the upper surface near one margin (fig. 300). The mechanical 

 tissue in F. tenera is represented by sub- epidermal girders in the 

 angular margins and below the mid-rib which is greatly projected 

 downwards. The mechanical tissue in leaf-blades of S. maritimus 

 (fig. 312) consists of I-sub-epidermal girders webs of which are formed 

 by mixed vascular bundles of the veins and of small sub- epidermal 

 girders in the margin and on the lower surface of the mid-rib. The 

 sub-epidermal girders in leaf-sheaths occur on the outer surface above 

 the veins and at the angles. 



The occurrence of extensive mechanical tissue on the lower 

 surface protects the lower surface against tension produced in the 

 upwards-curving movement of the leaf-halves which are brought 

 about by diminution in turgidity of the cells in the articulation tissue 

 in the upper half of the leaf-blade. 



Hairs, either clothing or glandular, are absent in all the members. 



Structure of the axis. — The epidermis consists of tabular cells with 

 outer walls flat, greatly thickened and silicified. Inner walls are very 

 thin and angular and lateral walls are thin and straight. Epidermal 

 cells between the girders in species of Scirpus are uniformly sclerosed. 



The assimilatory tissue in species of Cyperus and in F. tenera is 

 composed of girders and arcs of tabular palisade cells round smaller 

 veins and on sides of the upper portion of larger veins respectively. 

 In S. quinquefarius (figs. 309, 310) palisade tissue occurs between and 

 below the girders, while in 8. maritimus (fig. 315) it occurs between 

 the girders. 



