Page:The Journal of Indian Botany.djvu/134

 cavities with a lining layer of cells and with pinkish contents in Gossypium herbaceum. Oxalate of lime is found in the form clustered crystals in the soft bast in Sida grewioides and Gossypium herbaceum (fig. 60) in the cork, collenchyma, soft bast and pith of Abutilon fruticosum (fig. 56) and in the collenchyma of Hibiscus micranthus (fig. 58). Oxalate of lime does not occur in any form in Pavonia arabica.

Anamolous structures are represented by vascular bundles in the pith of Abutilon fruticosum as already mentioned.

General Review:—Epidermal cells are tabular with outer walls not much thickened. Large water-storing cells are intercalated amongst the ordinary epidermal cells in Hibiscus micranthus (fig. 57). Guard-cells are usually a little elevated. The front cavity is depressed. A dense covering of tufted hairs occurs on the leaves and young branches. External glands are either club-shaped (tig. 57), pitcher-shaped (fig, 54) or spherical (fig. 59) ; they are usually placed in epidermal depression.

The mesophyll is composed of palisade tissue on the adaxial side and of arm-palisade tissue on the abaxial side. Internal secretory organs occur in the leaf and axis in the form of secretory cells or secretory cavities. The veins are embedded except the larger ones in Abutilon fruticosum ; they are provided with bundle-sheaths. Oxalate of lime is found in the form of clustered crystals in the leaf and axis, The assimilatory tissue in the axis is either composed of palisade tissue or of chlorenchyma. The cortex is usually strengthened by collenchyma. The cork is subepidermal. The pericycle is formed of rhomboidal groups of stone-cells. Numerous small groups of bast fibres are found in the soft 'bast of Sida greiuioides and Pavonia arabica* The wood forms a composite hollow cylinder. The vessels are small and few. Interfascicular wood prosenchyma is not ex- tensive. Medullary rays are 1-3 seriate. Vascular bundles occur in the pith of Abutilon fruticosum. The pith is formed of thin-walled cells.

Melhania Denhamii Br. Pigs. 61, 62. Lower surface of leaf deeply furrowed. Mesophyll formed of short palisade cells on the adaxial side and of arm-palisade ones on the abaxial side. Upper epidermal cells with tanniniferous contents. Numerous mucilage canals in the pith. Solitary crystals in the leaf and axis. Clothing hairs tufted. Glandular hairs club-shaped. Pericycle formed of an outer loose ring of stone-cells and of an inner loose ring of bast fibres. Vessels large. Medullary rays 1-3 seriate and broadening outwards in the form of wedges between the groups of soft bast.