PLANTS OF THE INDIAN DESERT. 281 



the interior. The bundles are oonnected together by broad strips of 

 ground tissue which resemble medullary rays. Bundles in the inner 

 ring almost meet in the centre in Gitridlus Golocynthis and in 

 Melothria maderaspatana. The vessels expecially those of the bundles 

 of the inner ring have very wide lumina. 



A few cells of soft bast on either side of the bundles hold tanni- 

 niferous contents in all members etcept Momordica dioica. 



The pith is greatly reduced on account of the bundles of the inner 

 ring projecting inwards. It consists of a few thin-walled cells. 



General Review. — The epidermal cells have outer walls a little 

 thickened. The mesophyll is bifacial. Stomata are usually elevated 

 above the epidermis, much more so on the axis where they are usually 

 situated at the apex of pedestals formed by the subsidiary cells. The 

 stomata, as a rule, are more numerous on the lower surface of the leaf. 

 The hairy covering consists of uniseriate thin-walie I triohomes seated 

 on subsidiary ceils which, on the axis, are raised above the base of 

 the trichomes in the form of a pe lestal. The trichomas are some- 

 what jointed and more numerous on the lower surface of the leaf. 

 Internal secretory organs ate represented by a few isolated cells of 

 soft bast with tanniniferous contents in all members except Alomor- 

 dica dioica. The glandular hairs are placed in epidermal depressions 

 and consist of a short uniseriabe stalk and of an oval head divider by 

 horizontal and vertical walls. The pericycle forms a continuous and 

 undulated ring of stone-cells or it is formed of closely placed groups 

 of stone-sells. Gollenchyma is developed below the epidermis of 

 the angles. The vascular bundles are bicollateral and are situated 

 roughly in two rings. The bundles of the outer ring are much 

 smaller and are situated below the angles; bundles belonging to the 

 inner ring are much larger and are placed below the furrows; smaller 

 and larger bundles project outwards and inwards respectively. The 

 bundles are separated from one another by broad strips 01 ground 

 tissue resembling medullary rays. The vessels have wide lumina and 

 simple perforations. The pith is greatly reduced as the bundles of the 

 inner ring almost meet in the centre. 



FICOIDEAE 



Trianthema triquetra Bottl. & Wild.— Figs. 139, 140. Leaves 

 fleshy. Mesophyll characterised by an extensive aqueous tissue. 

 Stomata found only on the lower side of the leaf. Arcs of palisade 

 cells on the lower side. Veins embedded and half enclosed with green 

 bundle-sheaths. Clustered crystals found near the veins, in the cortex 

 and in the pith. Some of the epidermal cells bladder-like and atte- 

 nuated at the apices into hair-like structures, Axes angled, Wood 



