CHAPTER V
WOODS
Quite a mnnber oc dnx^ coosist of the wood of woody plants; sacfa dm^ arc qoassa. red sannders. white sandalwood, and
When studying woods it is necessary to ohser'e the cro6S, tangentiaL and radial sections. Such sections of quassia are shown in Plates 105. 106. and 107. ^lien studNing these sec- tions it should be remembered that while the types of cells form- ing quassia wood are similar to the cdb forming other woods, still their structure, arrangement, and amount will vary in a recognizable way in the different woods.
CROSS-SECTION QUASSIA
Plate 105 is a cross-section of quassia. It has the foUovring Structure:
Vessels. The vessds occur singly or in groups of two to ei^t cells. The cells are N-ariable in size and shape. The walls are yellowish white and porous.
MedoDaxy Rays. The medullary* ra>*s varj' from one to five cells in width.
The medoDaxy ray cells are radially elongated and the walls are stron^y porous.
Wood ParenchynuL The wood parenchyma cells have thin^ yellowish-white, an^ed walls.
Wood Fibres. The wood fibres have thick, yellowish-white, an^ed walls. These cells are smaller in diameter than the wood i>arench>Tna cells.
RADIAL SECTION QUASSIA
The radial section of quassia (Plate 107) is as follows: Vessels. The vessels appear as in the tangential section. Medullary rays. The medullary rays vary from ten to
254
{Picrxna t
Cross-Section of (Juassia Woe
Medullary rays.
Wood parenchyma.
Wood fibres.
Tangehtial Skctiok of Quassia \Vi
RaUal Sbctiok of Quassia Wood {Picrana excttsa [Sw.], Liiu
Showing the height and length o( the medullary raya and cells,
Cells with starch.
Wood parenchyma and wood fibres.
258 HISTOLOGY OF MEDICINAL PLANTS
twenty cells in height according to the part of the medullar}' ray bundle cut across.
The medullary ray cells exhibit their height and length. The walls of the cells are yellowish white and strongly porous.
Wood Parenchyma. The wood parenchyma cells have yellowish, thin walls and blunt end walls.
Wood Fibres. The wood fibres have thick, yellowish-white walls, and the end of the cells are strongly tapering.
TANGENTL\L SECTION QUASSIA
The tangential section of quassia (Plate io6) shows the following structure:
Vessels. The vessels are very long and broad and the yellow walls are marked with clearly defined pits.
Medullary Rays. The tangential section shows the cross- section of the medullary ray bundle and the cross-section of the medullary ray cell.
The medullary ray bundle varies in width from one to five cells. The ends of the bundles are always one cell in width, while the central part of the bundle is frequently five cells in width.
The medullary ray cell varies in size, structure, and shape according to the part of the cell cut across. The cells cut across the centre show hollow spaces, but the cells cut just above or below the end wall show a strongly pitted surface. The cells forming the end of the bundle are larger than the cells forming the centre of the bundle.
Wood Parenchyma. The wood parenchyma cells are greatly elongated and the walls are thin and yellowish white. The ends of the cells are blunt.
Wood Fibres. The wood fibres are elongated, the walls are thick and the cells are strongly tapering.
In quassia, white sandalwood, red sandalwood, and guaiac wood are characteristic crystals.
In quassia the vessels are finely pitted, yellowish, and dis- tinct; in white sandalwood the vessels are coarsely and sparingly pitted and white translucent; in red saunders the vessels are coarsely pitted, bright red and distinct.
WOODS 259
When studying woods we must consider the width of the medullary rays, the structure and cell contents of the medullary ray cells; the structure, color, and cell contents of the wood parenchyma; also the wood fibres.