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 cystoliths (calcium carbonate crystals). Glandular cells called trichomes are also present. These are capitate trichomes that have stalks. These trichomes secrete a resin (yellow) containing tetrahydrocannabinol, the active component of cannabis when used as a drug. Magnification: 220X when printed 10 cm wide.