Cystolith
CYSTOLITH (Gr. KVOTIS, cavity, andXlflos, stone), a botanical term for the inorganic concretions, usually of calcium carbonate, formed in a cellulose matrix in special cells, generally in the leaf of plants of certain families, e. g. Ficus elastica, the indiarubber plant.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)
