Calcium oxalate crystals in the stem and leaf of Cynanchum acutum . (A-C) Druse crystals in the cortex of the stem at different magnifications. (D) Druse crystals in the leaf mesophyll. (E) Druse crystals around the major vein. (F) Druse and prismatic crystals along vascular bundle. (Dc: Druse crystals; Pc: Prismatic crystals).