PLANTS OF THE INDIAN DESERT. 101 



numerous on the lower surface. Glandular hairs pitcher-shaped and 

 more numerous on the lower surface. Cortex characterised by cork 

 and collenchyma. Assimilatory tissue formed of chlorenchyma. Bast 

 fibres occurring in the soft bast. Wood uniformly broad. Medul- 

 lary rays uniseriate. Pith formed of thin-walled cells. 



Abutilon fruticosum Quill. — Figs. 55, 56. Woody. Stomata 

 numerous on both sides. Internal glands absent. Clustered crystals 

 found near the veins of the leaf and in the collenchyma, soft bast and 

 pith of the axis. Clothing hairs tufted and equally numerous on 

 both sides. External glands club-shaped and equally numerous on 

 both the sides. Cortex characterised by cork and collenchyma. 

 Wood uniformly broad. Vascular bundles occurring in the pith. 

 Medullary rays 1-3 seriate. Pith formed of thick-walled cells. 



Pavonia arabica Steud. — Woody. Stomata more numerous on 

 the lower surface. Secretory cavities numerous in the mesophyll. 

 Clustered crystals abundant in the leaf and axis. Clothing hairs 

 tufted and more numerous on the lower surface. Tufted hairs along 

 with simple thick-walled unicellular hairs found on the axis. Assimi- 

 latory tissue formed of chlorenchyma. Bast fibres occurring in the 

 soft bast. Wood reduced on the lower side of the inclined axis. 

 Medullary rays uniseriate. Pith formed of thin-walled cells. 



Hibiscus micranthus Lf— PI. VIII, figs. 57, 58. Woody. 

 Stomata more numerous on the lower surface. Internal glands absent 

 in the leaf and axis. Clustered crystals found near the veins in the leaf, 

 and in the collenchyma and pith of the axis. Clothing hairs tufted. 

 External glands club-shaped and few on the leaf and axis. Assimila- 

 tory tissue formed of palisade cells. Cortex characterised by collen- 

 chyma. Sclerenchymatous pericycle and wood reduced on the lower 

 side of the inclined axis. Medullary rays 1-3 seriate. Pith formed 

 of thin-walled cells. 



Gossypium herbaceum L— Figs. 59, 60. Woody. Stomata 

 more numerous on the lower surface. Internal glands in the leaf and 

 axis in the form secretory cells and secretory cavities. Some of the 

 pith cells holding tanniniferous contents. Clothing hairs tufted. 

 Glandular hairs spherical and more numerous on the upper surface 

 of the leaf and numerous on the axis. Cork subepidermal. Scleren- 

 chymatous pericycle and wood reduced on the lower side of the 

 inclined axis. Medullary rays 1-3 seriate. Pith formed of thin-walled 

 cells. 



Structure of the Leaf : — Epidermal cells are tabular with outer- 

 walls thickened and papillose. Lateral walls are straight. The sur- 

 face of the leaf in Abutilon fruticosum is characterised by ridges and 

 furrows. There are cells of considerable dimensions with water- 



