Page:The Journal of Indian Botany.djvu/57

 MENISPERMACEAE.

Cocculus cebatha DC. —Figs. 1, 2. (p. 39)— Epidermis of the leaf composed of thin-walled tabular cells. Stomatu occurring on both the surfaces. Subsidiary cells accompanying the guard-cells. Mesophyll composed wholly of palisade cells. Internal glands absent. Pith cells containing clusters of acicular crystals of oxalate of lime. Clothing hairs bicellular and curved. Glandular hairs absent. Veins embedded and enclosed in green sheaths. Axis slightly ribbed, ribs strengthened by a few sclerenchymatous fibres. Epidermal cells of the axis tabular with outer walls greatly thickened and cuticularised. Cortex formed of chlorophyll containing parenchyma. Pericycle composed of large groups of stone-cells. Wood formed of xylem bundles separated by broad medullary rays extending to the cortical chlorenchyma. Groups of cells resembling bast fibres on the inner face of the xylem bundles. Pith composed of thick-walled cells.

Structure of the leaf Epidermis is composed of tabular cells, with outer walls flat and a little thickened. Lateral and inner walls are thin and the former are straight. Stomata are accompanied by subsidiary cells and are more numerous on the under-surface. Guard-cells are situated on a level with the surrounding cells, with the front cavity slightly depressed, or on a level with the surface, fig 1. The mesophyll is composed of a homogeneous tissue of short palisade cells. Internal glands are absent in the leaf as well as in the stem. Oxalate of lime is not found in any form in the leaf. Veins are embedded and are enclosed in green bundle sheaths.

Veins of the mid-rib, which is prominent above and below, are verti- cally transcurrant above and below by collenchyma; the bundles are protected on the lower side by small groups of stone-cells.

Hairy covering on the leaf and axis consists of clothing hairs. Clothing hairs are made up of a short thin-walled basal cell and of a long curved thin- walled pointed terminal cell.

Structure of the axis Epidermal cells are small and tabular with outer walls very greatly thickened and cuticularised. Lateral and inner walls are thin and the former are straight. The axis is slightly ribbed, the ribs being strengthened by a few sclerenchymatous fibres.

The cortex is formed of chlorophyll containing parenchyma which extends to the medullary rays between the groups of stone-cells of the