8 THE JOURNAL OF INDIAN BOTANY. 



ASCLEPIADACEAE. 



Glossonema varhns Benth. -Leaves fleshly. Epidermal 

 cells with outer walls thickened. Guard-cells elevated. Mesophyll 

 formed of palisade tissue on the adaxial side and of arm-palisade on 

 the abaxial side. Cortical parenchyma extensive and formed of thin- 

 walled colourless cells. Pericycle composed of rhomboidal groups of 

 bast fibres with large lumina. Medullary rays uniseriate. Pith 

 consisting of thin-walled cells with brownish contents. 



Galotropis procera Br.— Figs. 197, 198 {Leaf only). Leaves 

 fleshy. Epidermal cells with outer walls greatly thickened. Cuticle 

 very thick. Guard-cells on the adaxial side situated quite below the 

 plane of epidermal cells ; those on the abaxial side elevated. Meso- 

 phyll consisting of extensive palisade tissue on the upper side and of 

 extensive loose arm-palisade tissue on the lower. Clothing hairs in 

 the form of very shorfe uniseriate trichomes. 



Pentatropis cynanchoides Br. — Leaves fleshly. Epidermal 

 cells with outer walls thickened. Guard-cells elevated. Mesophyll 

 wholly of arm-palisade tissue. Epidermis of the axis two-layered. 

 Oxalate of lime in the form of clustered crystals in cortex and soft 

 bast. Internal secretory cells with tanniniferous contents found in 

 cortex and pith. Pericycle formed of long thin groups of stone-cells. 

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



Sarcostemma brevistigma Wt.— Fig. 199. Leafless. Epi- 

 dermal cells longer than broad. Guard-cells quite below the plane of 

 epidermal cells. Cortical parenchyma extensive and aqueous. Peri- 

 cycle formed of rhomboidal groups of stone-cells. Medullary rays 

 uniseriate. Pith consisting of thin-walled cells with granular contents. 



Leptadenia spariium Wt. — Fig. 200. Almost leafless. Stomota 

 in depressions formed by thickened outer epidermal walls. Mesophyll 

 isobilateral. Clothing hairs in the form uniseriate trichomes with 

 vermcose walls. Epidermis of the axis three-layered. Internal secretory 

 cells with tanniniferous contents. Pericycle of rhomboidal groups 

 of stone-cells. Vessels large on the outer side and small on the inner 

 side. Medullary rays 1-2 seriate. Pith consisting of thin-walled cells. 



Structure of the Leaf. — -The epidermis is composed of small poly- 

 gonal cells in all members except in G. procera and P. cynanchoides 

 where the epidermal cells are tabular. The outer walls are thickened 

 and convexly arched outwards. The cuticle in C. procera is con- 

 siderably thickened (fig. 197). In G. procera and L. spartiirm it is 

 superficially granulated. The epidermal cells are alike on both the 

 surfaces except in G. variant and P. cynanchoides, where the epider- 

 mal cells on the upper side are much larger than those on the lower. 



