276 THE JOURNAL OF INDIAN BOTANY. 



Glandular hairs are of rare occurrence. They occur on the 

 upper surface of the leaf-blade of 0. Thomaeum, on the axis of G. 

 Boleana (fig. 342) and on the leaf-blade and axis of D. bispinata. 

 They are composed of a stalk-cell and of a club-shaped head which is 

 divided by horizontal walls. 



Structure of the axis. — The epidermal cells are small and have 

 the outer walls greatly thickened and silicified. The stomata are 

 accompanied by subsidiary cells. The guard-cells are elevated and 

 the front cavity is placed in a depression formed by outer thickened 

 epidermal walls. 



The cortex is characterised by an extensive sclerenchymatous 

 tissue with groups of the assimilatory tissue embedded in it. The 

 assimilatory tissue, in A. hirtigluma, P. turgidnm, E. interruputa, 

 E. aristata, and G. Royleana is composed of groups of palisade 

 cells which are separated from the stereome by single layers of thick- 

 walled cubical cells containing chlorophyll and resembling bundle- 

 sheath cells. 



The palisade cells form a continuous ring in P. elegans and 

 E. hirsutus. An assimilatory tissue is not found in D. sanguinalis, 

 E. Boyleanus, L. senegalensis and species of A ndropogon. In other 

 members the assimilatory tissue is chlorenchymatous and is not 

 accompanied by a sheath-like layer. 



The mechanical tissue in the axis is represented by a stereome 

 tube supplemented by isolated sub-epidermal girders of variable sizes 

 except in P. elegans and E. hirsutus. Flanges are given out from 

 the outer side of the stereome tube at more or less regular intervals 

 and in some cases (figs. 340, 355), they unite with supplementary 

 sub-epidermal girders, thus bringing the two systems into contact and 

 contributing additional strength to the whole mechanical system. In 

 species of Aristida (figs. 336, 337), Panicum (figs. 320, 322) and of 

 Eleusine (fig3. 348, 350), in P. elegans (fig. 352), G. Boyleanus (fig. 

 343) and C. catharticus (fig. 324) the smaller vascular bundles are 

 embedded in the stereome strands, formed by sub-epidermal girders 

 and by flanges of the stereome tube. 



The embedded small vascular bundles are mixed with the accom- 

 panying sheaths (fig. 320) only, or with both sheaths and girders of 

 the assimilatory tissue (figs. 340, 343, 352). In other cases where 

 the vascular bundles are embedded they are unmixed. This sort of 

 arrangement of the mechanical tissue is quite effective, as it forms an 

 adequate strengthening tissue without preventing the assimilatory 

 tissue from performing its function. 



In D. sanguinalis, E. Boyleanus, L. senegalensis and in species 



