Page:The Journal of Indian Botany.djvu/530

98 THE JOURNAL OF INDIAN BOTANY. the form of bundles of acicular or rod-like crystals in the pith cells of B. hochstetteri. Anamolous structures are represented by isolated thick-walled vessels in the pith of B. hochstetteri.

General Revieiu. — Epidermal cells have the outer walls thickened. There are large cells, containing rounded cystoliths, intercalated amongst ordinary epidermal cells. The stomata are accompanied by subsidiary cells. Mesophyll is either isobilateral or is composed of palisade tissue on the upper and of arm-palisade tissue on the lower side. Structures resembling internal glands are found in the mesophyll of some members. Oxalate of lime is found only in the pith cells of B. hochstetteri, in the form of bundles of acicular or rod-like crystals. Besides simple unicellular hairs or uniseriate trichomes which are of general occurrence, there are special forms of trichomes such as armed trichomes on the axis of B hochstetteri. External glands are found in all members. The assimilatory tissue in the axis is composed of chlorenchyma or of palisade cells. The collenchyma either forms groups or is found in the form of a more or less continuous ring, below the epidermis. An aqueous tissue is found in the leaf and axis of B. sindica. Sclerenchymatous pericycle occurs only in B. patula, in the form of isolated bast fibres. The wood forms a composite ring. The interfascicular wood prosenchyma is fairly extensive in members in which the vessels are not uniformly distributed. The pith consists of thin-walled or thick-walled cells. Anamolous structures are represented by thick-walled vessels in the pith of B. hochstetteri.

Boucbea marrubifolia Schemer.— Figs. 260, 261, 262. PI. XXVI. Epidermal cells tabular with outer walls very greatly thickened. Guard-cells accompanied by two subsidiary cells. External glands composed of a uniseriate stalk and of an elliposidal bicellular head. T. S. of the axis quadrangular. Pericycle formed of groups of the stone-cells. Cork absent.

Cleredendron Phlomidis L./.— Figs. 263, 264. Epidermal cells tabular with outer and inner wall equally a little thickened. Guard-ceils accompanied by 4-5 ordinary epidermal cells. External glands composed of a stalk-cell and of a broad elliptical head divided by many vertical walls. Pericycle forming a loose ring of stone-cells. Cork developed below collenchyma. T. S. of the axis circular.

Structure of the Leaf. — The epidermal cells are tabular with the outer and inner walls thickened, the thickening of the outer walls being considerable in B. marrubifolia (fig. 260). The lateral walls