Page:The Journal of Indian Botany.djvu/435

 striated. The epidermal cells at the margin have outer walls convexly arched outwards and have both the inner and outer walls thickened. The margins are strengthened by a few collenchymatous cells. The stomata occur abundantly on both the surfaces and are surrounded by ordinary epidermal cells. The guard-cells are elevated and the front cavity is on a level with the surface. The mesophyll is formed of a homogeneous tissue of horizontally elongated polygonal assimila- tory cells. Internal secretory organs are found neither in the leaf nor in the axis.

The leaves are many-ribbed and the veins of the ribs are vertically transcurrent above and below by collenchyma. The smaller veins are embedded. The vascular bundles of the veins are bicollateral.

Clothing as well as glandular hairs do not occur on the leaf and axis.

Structure of the Axis. — The axis is irregularly ribbed, some of the ribs being wing-like. The ribs are strengthened by collenchyma. The epidermis consists of tabular cells with both outer and inner walls thickened. The cuticle is striated. The cortex is composed of chloren- chyma which extends to the ribs.

A sclerenchymatous pericycle is not developed. The wood is composite and is broader below the ribs. The vessels are small and are arranged almost in complete rows. Interfascicular wood prosen- chyma is little developed. The medullary rays are uniseriate and numerous. The vascular bundles are bicollateral and have two con- tinuous rings of soft bast — one on the outer and another on the inner side of the wood cylinder. The pith is composed of thin-walled cells.

Oxalate of lime occurs in the form of star-like clusters of acicular crystals in cortical parenchyma and pith.