Many plant cells contain crystalline inclusions of different chemical composition and shape. Crystalline aggregations are called druses, bundles of needle-shaped crystals are termed raphids. The scanning electron microscopic images show: Upper picture: a calcium oxalate druse in the mesophyll cells of an oleander leaf (Nerium oleander). It has the typical druse shape of dicots. Middle picture: calcium oxalate needles (raphids) in cells of a vanilla root (Orchidaceae). These are the typical raphid bundles of monocots. Lower picture: silicate bodies of silicate cells in the epidermis of Schizachyrium sanguineum (a Gramineae species of the old world tropics). Characteristic mineralization of a Gramineae cell. [W. BARTHLOTT, MARTENS, 1979 (c), W. BARTHLOTT, unpublished (a, b)]