# Trichome

> A hair-like outgrowth of the plant's skin; in cannabis the glandular types make and store the resin holding cannabinoids and terpenes.

- Canonical: https://genetixbay.com/knowledge/glossary/trichome.html
- Also written: trichomes, resin glands, resin heads, crystals, glandular hairs
- Glossary category: Plant biology · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

A trichome is any hair or outgrowth from the epidermis of a plant. Cannabis has two broad groups. [Non-glandular trichomes](https://genetixbay.com/knowledge/glossary/cystolith-trichome.md) are simple pointed [hairs](https://genetixbay.com/knowledge/glossary/pistil.md) that protect the surface. Glandular trichomes are secretory: a disc of cells makes resin rich in cannabinoid acids (such as [THCA](https://genetixbay.com/knowledge/glossary/thca.md) and CBDA) and terpenes and stores it in a cavity under a waxy cuticle at the gland head.

## In practice

The three glandular types are bulbous (tiny), capitate-sessile (on leaves and early flowers) and [capitate-stalked](https://genetixbay.com/knowledge/glossary/capitate-stalked-trichome.md) (the mushroom-shaped glands on bracts that hold most of the resin). When growers say "frost", "crystals" or "trichomes", they almost always mean capitate-stalked heads.

With a 60-100x loupe or microscope, head colour shows maturity: clear, then cloudy (milky), then amber. GenetixBay's harvest guidance is a matter of taste, ideally a mix of a few clear, mostly cloudy and some amber heads.

[Trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md) are fragile. Rough handling, warm temperatures and agitation knock them off, which matters for trimming and storage.

## Don't confuse with

- **Pistil (stigma)**: the white or orange hairs of the flower, not resin glands.
- **Kief**: loose detached trichome heads, a processing term.
- **Powdery mildew**: a fungal coating that sits flat on leaf surfaces, not on stalks.

## Myth check

Frost is not potency. Visible trichome density did not reliably predict [THC](https://genetixbay.com/knowledge/glossary/thc.md) in field work, and [bag appeal](https://genetixbay.com/knowledge/glossary/bag-appeal.md) is not quality (Supported). See [Mythbusters](https://genetixbay.com/knowledge/mythbusters.md).

## Related terms

[Capitate-stalked trichome](https://genetixbay.com/knowledge/glossary/capitate-stalked-trichome.md), [Capitate-sessile trichome](https://genetixbay.com/knowledge/glossary/capitate-sessile-trichome.md), [Bulbous trichome](https://genetixbay.com/knowledge/glossary/bulbous-trichome.md), [Cystolith trichome](https://genetixbay.com/knowledge/glossary/cystolith-trichome.md), [Trichome ripeness](https://genetixbay.com/knowledge/glossary/trichome-ripeness.md)

## Read more

- [Trichome ripeness: clear, cloudy, amber, and what the evidence says](https://genetixbay.com/knowledge/harvest-cure/trichome-ripeness.md)
- [Cannabis plant biology: the parts and what they do](https://genetixbay.com/knowledge/basics/cannabis-plant-biology.md)

## Sources

1. Livingston SJ, Quilichini TD, Booth JK, et al. 2020. Cannabis glandular trichomes alter morphology and metabolite content during flower maturation. The Plant Journal 101(1):37-56. https://doi.org/10.1111/tpj.14516
2. Punja ZK, Sutton DB, Kim T. 2023. Glandular trichome development, morphology, and maturation are influenced by plant age and genotype in high THC-containing cannabis (Cannabis sativa L.) inflorescences. Journal of Cannabis Research 5:12. https://doi.org/10.1186/s42238-023-00178-9