a mineral concretion, usually crystals of calcium carbonate, within the epidermal cell of the leaves of some plants, (for example Urticaceae), almost always visible as light coloured spots in the leaves.
Copyright: Mark Hyde, Bart Wursten, Petra Ballings and Meg Coates Palgrave, 2002-17
Hyde, M.A., Wursten, B.T., Ballings, P. & Coates Palgrave, M.
. Flora of Zimbabwe: Glossary details: cystolith.
http://www.zimbabweflora.co.zw/speciesdata/glossary-display.php?glossary_id=196, retrieved 30 March 2017