1. Quassia (Picræna excelsa [Swartz.], Lindl.).
2. Uva-ursi leaf (Arctostaphylos uva-ursi [L.], Spring.).
3. Quebracho bark (Aspidosperma quebracho-blanco, Schlechtendal).
4. Wild-cherry bark (Prunus serotina, Ehrh.).
PLATE 87
Rosette Crystals and Solitary Crystals Occurring in
1. Cascara sagrada bark (Rhamnus purshiana, D.C.).
2. Frangula bark (Rhamnus frangula, L.).
3. Cundurango bark (Marsdenia cundurango, [Triana] Nichols).
4. Dogwood root bark (Cornus florida, L.).
5. Pleurisy root (Asclepias tuberosa, L.).
PLATE 88
Cystoliths
1. Ruellia root (Ruellia ciliosa, Pursh.).
2. Pellionia leaf.
3. Cannabis indica (Cannabis sativa, variety Indica, Lam.).
Cystoliths occur, then, in special cavities, in parenchyma cells (rubber-plant leaf, fig, pellionea, and mulberry), and in non-glandular hairs (cannabis indica).
In powdered ruellia root the cystoliths occur in or are separated from the parenchyma cells.