Light micrograph of glandular trichomes of a Cannabis sativa bract, a medicinal plant and recreational drug. The trichomes in Cannabis secrete cannabinoids, terpenoids, flavonoids and other compounds, most abundantly on the floral calyxes and bracts of female plants. They play a critical role in plant protection against various environmental stresses, including herbivore attack, pathogen infection, extreme temperature and excessive light. The stalked glandular trichomes are comprised of a stalk with a resin head at the top. The highest concentration of psychoactive THC is located at the base of the resin head, especially when it reaches a transparent to creamy-white colour. Cystolith trichomes have a pointed tip and are long and hair-like. They exude insecticidal and miticidal substances. The bulbous trichomes are ball-shaped and have no stalk. Field of view size: 0.96 x 1.45 mm (0.038 x 0.057 in)