Trichomes are epidermal outgrowths, glandular surface hairs that produce, in the case of cannabis, a broad range of cannabinoids. This is also how mint leaves make and store their mint oil. Cannabis trichomes produce and house not only THC but hundreds of other medicinally valuable compounds.

For some carnivorous plants, their trichomes help them catch prey. For cannabis, its trichomes protect the plant acting as a natural bug and animal repellant while shielding the plant further from wind, UV rays and some bacteria. This is similar to coffee where caffeine, the part we're after, is actually the plant's natural bug repellant.

As the cannabis plant begins to flower, trichomes appear all along the surface. With further growth and time, the gland heads start to metabolize cannabinoids.

Type and concentration of cannabinoids depends on, like wine, genetics and environmental factors. These include not only the amount of light but the spectrum or type of light. Typically, plants that receive a broader spectrum of light will produce higher concentrations of cannabinoids, though results and reactions are strain-specific.

Trichomes are extracted from the plant by a few methods and techniques. Dry sifting produces kief. Chemical extractions using hydrocarbons create waxy oils. If extracted correctly, these valuable cannabinoid-rich trichomes can be stored indefinitely.