An appendage on the surface of the cannabis flower that produces and holds the plant's cannabinoids and terpenes. Trichomes are primarily produced on the flower, bract, and leaves of the cannabis plant. They have a sugary, crystal-like appearance.

This bud is covered in trichomes. Look how frosty and sticky it is. 

If you're going to make dry sift, use freeze-dried cannabis so the trichomes break off the plant more easily.

cannabis plant trichomes Photo by: Gina Coleman/Weedmaps

What is a trichome?

Trichomes are the glandular and non-glandular “hairs” found on the surface of plants and are responsible for producing the cannabis plant's cannabinoids and terpenes. Though you may not have known what they were, you've probably noticed trichomes as the tiny hairs that cover your cannabis, giving it a crystal-like sheen and sticky feel.

What are trichomes made of?

Trichomes may be made of hairs, glandular hairs, scales, and papillae. They grow on the appendages of plants, such as cannabis, as well as algae and lichens. 

What is the difference between trichomes and root hairs?

Trichomes and root hairs are found in different places on a plant. Whereas root hairs are observed in the young roots near a plant's tips, trichomes are more widespread and cover the entire stem as well as leaves and flowers. There are also cellular differences between trichomes and root hairs. Root hairs are exclusively unicellular while trichomes may be unicellular or multicellular. 

What are trichomes on weed?

While they're most visible to the naked eye on cannabis flower, trichomes can also be found on the leaves and stems of the plant. They contain resin glands that make the terpenes, THCA, CBDA, and other phytocannabinoids for which cannabis is known.  

close up cannabis plant Photo by: Gina Coleman/Weedmaps

What are the functions of trichomes?

During cultivation, trichomes function in part as deterrents to pests, predators, and environmental stresses on the plant. They help the plant maintain optimal surface-level humidity so it doesn't dry out, and produce terpenes that repel insects. The small bulbous trichome glands can also trap and confine smaller insects.

What do trichomes do?

Trichomes fall into two categories: glandular and nonglandular. Only glandular trichomes produce cannabinoids. Nonglandular trichomes are called cystoliths and serve primarily as a defense mechanism for the plant by impaling small insects. Glandular trichomes can be further separated into three categories:

Bulbous trichomes are tiny bulbs that dot the surface of the plant. They cannot be seen without a microscope. While their production of cannabinoids is still in question, they add a crystal-like sheen to the cannabis plant and add to the stickiness of the flower. Bulbous trichomes are not specific to any particular area of the plant; they are evenly distributed throughout its surface. 

Capitate-sessile trichomes are more abundant than bulbous trichomes, but still typically only visible with the aid of a microscope. Like bulbous trichomes, capitate-sessile trichomes have large bulbs  with more a classic mushroom structure. They also have secretory cells at the base, which initiate cannabinoid and terpene biosynthesis. This type of trichome is primarily found on the underside of the sugar and fan leaves.

Capitate-stalked trichomes are shaped like mushrooms and contain a large bulb at the head of a stalk. The bulb contains secretory cells at its base, and nutrients are transferred to the head through the multicellular stalk. Before they fully form, capitate-stalked trichomes look identical to sessile trichomes. They are the largest and most abundant trichomes in cannabis, and their shape is most familiar to consumers because they can be easily seen with the naked eye. The stalked trichome is primarily found on the surface of cannabis flowers and rarely seen on sugar or fan leaves. 

When do trichomes appear? As trichome heads age, they go from being completely clear to an opaque, milky white, then to brown after excessive aging. If trichomes are visibly brown, the cannabis plant has probably aged past peak potency.

How cannabinoids are created in trichomes

Cannabinoids are produced within the trichome cells through biosynthesis, in which enzymes catalyze a series of chemical reactions to produce complex molecules from simple (smaller) molecules.

The three basic steps for cannabinoid biosynthesis are binding, prenylation, and cyclization. Molecules called enzymes bind to one or two small molecules called substrates, attach the substrates to each other, then pass the transformed substrate down an assembly line to another enzyme that processes it, cycling the small molecule through further sequential changes.

The enzymes responsible for producing the cannabinoids with which most of us are familiar are cannabidiolic acid (CBDA) synthase, cannabichromenic acid (CBCA) synthase, and tetrahydrocannabinolic acid (THCA) synthase. These enzymes take the central cannabinoid precursors, cannabigerovarin acid (CBGVA) and cannabigerolic acid (CBGA), and convert them into acidic cannabinoids such as THCA and CBDA.

From here, these cannabinoids may be altered further through decarboxylation. When a chemical compound decarboxylates, it loses a carbon atom along with two oxygen atoms and releases carbon dioxide, either by heat or prolonged overexposure to environmental stress. THCA and CBDA decarboxylate into tetrahydrocannabinol (THC) and cannabidiol (CBD), respectively, and must do so to exhibit their characteristic effects. This is considered a degradation process because it does not require enzymes and occurs after the plant is harvested.

Trichomes in concentrates

Cannabis concentrates isolate and accumulate the plant's desirable compounds from its trichome glands. The two modes of separating trichomes from the cannabis plant are physical separation and chemical extraction. 

Physical separation, also known as mechanical separation, involves breaking and removing trichomes from plant material via a physical action such as shaking or pressing. Think of it like shaking a fruit tree to release the ripe fruit. Dry sift or kief, for example, is made by shaking cured cannabis through a series of screens in specific sizes to ensure nothing but trichome glands make it into the final product.

Chemical extraction, also known as solvent-based extraction, utilizes a chemical solvent to dissolve the trichomes from the plant. Solvent-based extraction is the most efficient method in the removal of trichomes from the cannabis plant and is the preferred method for the commercial cannabis industry.

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The information contained in this site is provided for informational purposes only, and should not be construed as medical or legal advice. This page was last updated on February 1, 2021.