Cannabis plant. Coloured scanning electron micrograph (SEM) of the surface of a cannabis (Cannabis sativa) plant. The pointed hairs are called lithocyst cells. They contain cystolyths (calcium carbonate crystals). Glandular cells called trichomes are also present. These are capitate trichomes tbat have stalks. Trichomes secrete a resin containing tetrahydrocannabinol. The resin is the source of a euphoriant drug. Magnification unknown.