In powdered drugs, stone cells, like bast fibres, occur singly, as in ruellia, calumba, etc.; or in groups, as in cascara sagrada, witch-hazel bark, etc. In most powders they occur both singly and in groups.
The individual stone cells are mostly entire, as in ruellia, calumba, allspice, echinacea, etc. In cascara sagrada many of the stone cells are broken when the closely cemented groups are torn apart in the milling process. Many of the branched stone cells of witch-hazel bark and leaf, wild cherry, etc., also occur broken in the powder.
PLATE 32
Porous and Striated Stone Cells
1. Ruellia root (Ruellia ciliosa, Pursh.).
2. Winter’s-bark (Drimys winteri, Forst.).
3. Bitterroot (Apocynum androsæmifolium, L.).
4. Allspice (Pimenta officinalis, Lindl.).
5. Aconite (Aconitum napellus, L.).
PLATE 33
Porous and Non-striated Stone Cells
1. Ceylon cinnamon (cinnamomum zeylanicum, Nees).
2. Calumba root (Jateorhiza palmata, [Lam.] Miers).
3. Dogwood root bark (Cornus florida, L.).
4. Cubeb (Piper cubeba, L., f.)
5. Echinacea (Echinacea angustifolia, D.C.).
PLATE 34