Calcium carbonate crystals in leaves of Ficus.

Ficus leaves are rich in minerals among which calcium carbonate (lithocysts), calcium oxalate and silica.
You will find on this page micrographs illustrating cystoliths, calcium carbonate crystals in large cells called lithocysts.

The two first micrographs show paraffin cross sections stained with astra blue – basic fuchsin in a leaf of ficus. In the upper micrograph we observe a cystolith in a specialized large epidermal cell (violet arrow) attached to the cell wall by a foot.

The second micrograph illustrates a specialized cell of parenchyma (idioblast) containing aggregates of calcium oxalate crystals.
pp: palissade parenchyma; pl:spongy parenchyma.

See also the section in a leaf of Ficus macrophylla