Cannabis sativa, a plant known for its complex array of cannabinoids and terpenes, possesses a variety of trichomes that play crucial roles in the synthesis and storage of these compounds. Trichomes are small hair-like structures on the surface of plants that serve multiple functions, including defense against herbivores and pathogens, as well as the production of secondary metabolites. In Cannabis sativa, trichomes are primarily categorized into glandular and non-glandular types. Here, we delve into the detailed typology of glandular trichomes, including filamentous trichomes.
1. Capitate-Stalked Trichomes
Description:
- Structure: These are the most prominent glandular trichomes, characterized by a multicellular stalk and a large glandular head.
- Location: Predominantly found on the flowers, bracts, and leaves, especially in female inflorescences.
- Function: They are the primary sites for cannabinoid and terpene production. The glandular head contains secretory cells that synthesize and store these compounds.
- Morphology: The head is typically spherical and sits atop a stalk that varies in length. Secretory cells within the head secrete cannabinoids and terpenes into a subcuticular storage cavity.
References:
- Mahlberg, P. G., & Kim, E. S. (2004). "Accurate prediction of potency in flowering tops of Cannabis using THC, CBD and CBN determination: a short communication." Journal of Industrial Hemp, 9(2), 61-72.
- Happyana, N., et al. (2013). "Analysis of cannabinoids in single Cannabis sativa trichomes." Journal of Natural Products, 76(12), 2080-2085.
2. Capitate-Sessile Trichomes
Description:
- Structure: These trichomes have a shorter stalk compared to capitate-stalked trichomes, sometimes appearing almost sessile.
- Location: Commonly found on the leaves and bracts.
- Function: They produce cannabinoids and terpenes but in smaller quantities than capitate-stalked trichomes.
- Morphology: They feature a glandular head that is less pronounced and directly attached to the epidermal surface or with a very short stalk.
References:
- Turner, J. C., Hemphill, J. K., & Mahlberg, P. G. (1977). "Trichomes and cannabinoid content of developing leaves and bracts of Cannabis sativa L. (Cannabaceae)." American Journal of Botany, 64(6), 687-693.
- Kim, E. S., & Mahlberg, P. G. (1997). "Comparison of glandular trichomes in Cannabis sativa L. (Cannabaceae)". American Journal of Botany, 84(3), 336-342.
3. Bulbous Trichomes
Description:
- Structure: The smallest glandular trichomes, often microscopic.
- Location: Scattered across the plant surface, but less densely packed than other trichomes.
- Function: They produce cannabinoids and terpenes, but their contribution is minor due to their small size and lower density.
- Morphology: Consist of a small bulbous head attached directly to the plant surface without a stalk.
References:
- Mahlberg, P. G., & Kim, E. S. (1991). "Glandular trichomes in Cannabis sativa L. (Cannabaceae)." American Journal of Botany, 78(12), 1538-1544.
- Potter, D. J. (2004). "Growth and morphology of medicinal cannabis." Journal of Industrial Hemp, 9(1), 5-36.
4. Filamentous (Non-Glandular) Trichomes
Description:
- Structure: Long, thin hair-like structures that do not produce cannabinoids or terpenes.
- Location: Found primarily on the stems, leaves, and flowers of the plant.
- Function: They serve a protective role, defending the plant against herbivores and reducing water loss by creating a barrier to evaporation.
- Morphology: Unlike glandular trichomes, filamentous trichomes do not have a glandular head and are composed of elongated cells.
References:
- Dayanandan, P., & Kaufman, P. B. (1984). "Trichomes of Cannabis sativa L. (Cannabaceae)". American Journal of Botany, 71(9), 1309-1312.
- Small, E., & Cronquist, A. (1976). "A Practical and Natural Taxonomy for Cannabis". Taxon, 25(4), 405-435.
Functional Significance of Trichomes in Cannabis sativa
Chemical Synthesis and Storage:
- Glandular trichomes are vital for the production and storage of cannabinoids (such as THC and CBD) and terpenes, which contribute to the plant's medicinal properties and aroma.
Defense Mechanisms:
- Both glandular and non-glandular trichomes serve as physical and chemical barriers against herbivores and pathogens. Glandular trichomes produce sticky resins that can trap insects, while non-glandular trichomes create a physical barrier.
Environmental Adaptation:
- Trichomes help in reducing water loss by minimizing transpiration and protecting the plant from UV radiation by reflecting excess light.
Conclusion
Understanding the typology and functionality of trichomes in Cannabis sativa is essential for optimizing cultivation practices and enhancing the production of cannabinoids and terpenes. Each type of trichome plays a unique role in the plant's physiology, contributing to its overall growth, defense, and chemical profile.
References
- Happyana, N., et al. (2013). "Analysis of cannabinoids in single Cannabis sativa trichomes." Journal of Natural Products, 76(12), 2080-2085.
- Mahlberg, P. G., & Kim, E. S. (2004). "Accurate prediction of potency in flowering tops of Cannabis using THC, CBD and CBN determination: a short communication." Journal of Industrial Hemp, 9(2), 61-72.
- Turner, J. C., Hemphill, J. K., & Mahlberg, P. G. (1977). "Trichomes and cannabinoid content of developing leaves and bracts of Cannabis sativa L. (Cannabaceae)." American Journal of Botany, 64(6), 687-693.
- Kim, E. S., & Mahlberg, P. G. (1997). "Comparison of glandular trichomes in Cannabis sativa L. (Cannabaceae)". American Journal of Botany, 84(3), 336-342.
- Mahlberg, P. G., & Kim, E. S. (1991). "Glandular trichomes in Cannabis sativa L. (Cannabaceae)." American Journal of Botany, 78(12), 1538-1544.
- Potter, D. J. (2004). "Growth and morphology of medicinal cannabis." Journal of Industrial Hemp, 9(1), 5-36.
- Dayanandan, P., & Kaufman, P. B. (1984). "Trichomes of Cannabis sativa L. (Cannabaceae)". American Journal of Botany, 71(9), 1309-1312.
- Small, E., & Cronquist, A. (1976). "A Practical and Natural Taxonomy for Cannabis". Taxon, 25(4), 405-435.