Page:The Journal of Indian Botany.djvu/499

 cular wood-prosenchyma. This narrowed portion of the wood-ring represent the lower side of the inclined axis where the functional activity is comparatively much less. In addition to the normal zona of soft bast on the outer side of the wood-ring there are groups of intraxilary soft bast on its inner side. Intraxilary soft bast is protected on its inner side by groups stone-cells. The pith consists of thin-walled cells. Some of the pith cells contain crystal sand.

General Review : — The epidermal cells have their outer walls greatly thickened and cuticularised. The stomata are depressed and occur on both the surfaces ; they are surrounded by ordinary opidermal cells. The mesophyll is bifacial or is isobilateral. Oxalate of limo occurs abundantly in the form of crystal sand in the leaf and axis. The clothing hairs usually consist of a biseriate or multiseriate stalk and of a tuft of ray cells. In addition to the tufted hairs, uniseriate trichomes are found in S. albicaule. Glandular hairs are composed of a short uniseriate stalk and of an ellipsoidal head which is irregularly divided. The epidermis of the axis is one-layered or many-layered. The cork is sub-epidermal. The sclerenchymatous pericycle, when present, forms a loose ring of bast fibres. All the members are characterised by the occurrence of intraxilary soft bast. The vessels have simple perforations. The interfascicular wood prosenchyma is extensive. The medullary rays are uniseriate and numerous. Wood parenchyma is little developed. Pith consists of thin- walled cells. (To be continued.)