188 THE JOURNAL OF INDIAN BOTANY. 



lular and with muriculate walls. Glandular hairs formed of a short 

 uniseriate stalk and of an obconical unicellular head. Oxalate of lime 

 found in the form of clustered crystals. Leaf many-ribbed. Veins 

 of the ribs vertically transcurrent. Smaller veins embedded. 



Structure of the Leaf. — The epidermal cells are polygonal with 

 outer walls papillose much more so on the lower surface. The outer 

 and inner walls are equally thickened. Inner walls are convexly 

 arched inwards, thus coming into close contact with the assimilatory 

 tissue. The lateral walls are thin and undulated. The stomata are 

 more numerous on the lower surface and are ^accompanied by 

 ordinary epidermal cells. Guard-cells are situated in the plane of 

 the outer epidermal walls ; and the front cavity Ms on a level with 

 the surface. 



The hairy covering consists of clothing and glandular hairs \ 

 the former are more numerous* on the lower surface and the latter 

 more numerous on the upper. The clothing hairs are unicellular and 

 have muriculate walls ; the basal portion is conical and is inserted 

 between the epidermal cells (figs. 79, 81). Glandular hairs are formed 

 of a short uriseriate stalk and of an obconical head (figs. 79, 80). 



The mesophyll is composed of a layer of very long palisade 

 cells on the adaxial side and of an arm-palisade tissue on the abaxial 

 side. The elongated form of the palisade cells affords protection, 

 against intense light, to the chlorophyll grains. The greatly elongated 

 palisade cells, the development of arm-palisade tissue and the thicken- 

 ing of the outer and inner epidermal walls are distinct proofs of 

 xerophytic characters developed by the plant. Internal secretory 

 organs are not found in the leaf or axis. Oxalate of lime occurs 

 in the form of clustered crystals near the veins. 



The leaves are many-ribbed. The ribs are prominent below 

 and grooved above. The veins of the ribs are vertically transcurrent 

 above by colourless parenchyma and below by collenchyma. Smaller 

 veins are embedded. Bundle-sheaths are not found round the veins 



SIMARUBA.CEAE. 



Balanites Roxburghii Planch.— Figs. 82. 83, 84. Epidermal 

 cells of the leaf and axis tabular. Mesophyill- bifacial. Stomata de- 

 pressed with guard-cells below the plane of the sorrounding cells. 

 Internal glands absent. Oxalate of lime found in the form of solitary 

 and clustered crystals in the leaf and axis. Veins embedded and en- 

 closed in bundle sheaths. Groups of water-storing tracheids occurring 

 at intervals between the veins. Clothing hairs "present in the form 

 of short thick-walled unicellular trichomes. Glandular hairs absent. 

 Assimilatory tissue in the axis formed of chloreuchyma. Cortical 



