They have various functions such as storage of oils or other compounds and often contain chemicals, normally in crystalline format such as acrid tasting and poisonous calcium oxalate or carbonate or silica.
They have various functions such as storage of reserves, excretory materials, pigments and minerals. They could contain oil, latex, gum, resin, tannin or pigments etc. Some can contain mineral crystals such as acrid tasting and poisonous calcium oxalate or carbonate or silica.