The sieve cells are small and the walls are white and angled.
The vessels have thick, white, angled walls.
The bast fibres are rounded in outline and the walls are thick and white.
Endodermis. The endodermal cells encircle the fibro-vascular bundles. The cells are large, thin-walled, and oval in shape.
Secretion Cells. Near the edges of the leaf are schizogenous secretion cavities surrounded by thin-walled secretion cells.
POWDERED KLIP BUCHU
When the leaf is powdered (Plate 109), the cells are quite as characteristic in appearance. The upper epidermal cells (1) have thick-beaded, yellowish-white walls and papillate outer walls. No stomata occur on the upper surface. The under epidermis (2) with numerous stomata, is surrounded by the characteristic guard cells. The end walls are beaded as on the upper surface. The palisade cells (3) appear as in the cross-section. The conducting cells (4 and 4) are of the spiral and pitted type. The papillæ (5 and 5) are very abundant in the powder and very characteristic. The fragments of the epidermis (6) are also abundant. The mesophyll (7) is characteristic, as it retains its form when powdered. The fibres (8) are usually associated with the conducting cells; occasionally they are found free as in the illustration.
PLATE 109
Powdered Klip Buchu
1. Upper epidermis. 2. Under epidermis. 3. Palisade cells with chlorophyll. 4 and 4. Conducting cells. 5 and 5. Papillæ. 6. Fragments of the epidermis. 7. Mesophyll. 8. Fibres.