Page:The Journal of Indian Botany.djvu/498

 Cells with crystal sand occur in medullary rays and outer soft bast of S. incanum and L. barbarian. Crystal sand occurs abundantly in cortex and inner soft bast of S. incanum. The abundance of oxalate of lime in the leaf and axis gives an acrid taste to the tissues of the plants and prevents them from being easily devoured by animals.

Veins are embedded and are not provided with bundle-sheaths.

The hairy covering consists of clothing and glandular hairs. The clothing hairs on the leaf and axis of both the species of Solatium are tufted. They consist, in S. albicaule, of a short biseriate stalk and of a tuft'of ray-cells, some of the rays being uniseriate (fig. 236). In S. incanum (fig. 242), the stalk is multiseriate and is usually longer on the axis. In addition to the tufted hairs in <S. albicaule, there are uniseriate trichomes (fig. 238). Clothing hairs are absent in L. barbarum.

Glandular hairs occur in leaf and axis of L. barbarian and of both the species of Solanum ; and are composed of a short uniseriate stalk and of an ellipsoidal head which is irregularly divided (fig. 237).

Structure of the Axis. — The epidermis consists of a single layer of tabular cells with the outer walls greatly thickened and convexly arched outwards in S. incanum and L- barbarian. The epidermis in S. albicaule is composed of more than one layer (three layers in the specimen examined) of vertically tabular cells which are uniformly thickened a little on all sides. The epidermal cells of L. barbarian are mostly filled with crystal sand. The cortex in S. incanum, and L. barbarian is characterised by cork which is subepidermal. Cork in L. barbarian is strengthened by isolated stone-cells. The collen- chyma is subepidermal as in S. albicaule, or it occurs below the cork as in other members. In <S. incanum collenchyma is extensive and the inner portion of the cortex consist of large polygonal cells, some of which are filled with crystal sand.

The pericycle forms a loose ring of bast fibres in both the species of Solanuvi. Scleranchymatous pericycle is '■ not developed in L. barbarian.

The wood is composite in all members. Medullary rays are uniseriate and numerous. The vessels are few and large and are uniformly distributed in rows in the wood ring of S. albicaule and L. barbarian ; interfascicular wood prosenchyma is extensive and consists of cells with thickened walls and with small lumen. In S. incanum the vessels are large and are arranged in bundles which are connected by strands of interfascicular wood prosenchyma, formed of cells with thin walls and large lumen. The wood-ring in S. incanum is narrowed in a small portion on one side where it con- sists of a few vessels and of extensive connecting strands of interfasci-