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Cannabis Anatomy- Why the Plant Differentiation

Cannabis sativa is dioecious, meaning there are separate plants for each sex. In certain crops, cultivators desire particular plants. For the CBD flower production, it requires only females, whereas the crops for fiber and seed utilize both sexes. It is important to understand each plant in order to understand the value and role of each sex in the scope of the hemp industry.


Females vs Males


Females


Female plants contain the trichome-rich flowers, which is where the secondary metabolites are formed. Secondary metabolites refer to a plant’s ability to produce complex phytochemistry to serve as protection against predators and diseases as well as to attract pollinators. Cultivators realized long ago that by separating the males from the females, the females will produce more flowers and will be more potent than the ones that were fertilized. The reality is, the more time the females remain unpollinated, the more flowers are created and are increased in size (DeDecker, 2019). This isolating method is currently practiced by all CBD growers because they want to get the highest yield of cannabinoids from these flowers.


In cultivating females exclusively, there are some risks to be aware of in order to minimize crop failure. Before even putting plants in the ground, cultivators need to make sure they are not downwind of any fiber or seed grower, or that they are far enough away from their neighbors because these are wind-pollinated plants. If the plants were started from seeds, observe the garden for any rogue males after about 3-6 weeks. The male and female will develop pre-flowers a few weeks into their life cycle. They both will sprout at the node sites, but they are structurally different. The male pre-flower will lack the threadlike hairs known as stigmas; instead, they have stamens. The female pre-flowers contain the stigmas. The role of the stigma is to catch the pollen. Once males are spotted, they must be culled, but they can be used for breeding if they are carefully removed. The last thing to look out for are hermaphrodites amongst the females because they will pollinate everyone; therefore reduce potential stressors to avoid this happening and always start with quality genetics.


Females - Stigmas


Trichomes 101


Trichomes are small outgrowths ranging as thin hairs to bulbous glands on a plant’s epidermis that serve to protect a plant from pests, disease and other environmental factors. Some plants produce certain types, which can secrete various substances (resins, oils) and others provide a physical barrier deterring pests from latching on.


Close-up of Trichomes


Trichomes in cannabis serve as a self-defense mechanism, since they secrete resin from their glands; some of these are visible with the naked eye and some need magnification to see their structure. The trichomes that are readily visible are mostly glandular in shape and look like small mushrooms. From a distance, the flowers look as if they are encrusted with crystals. The glandular shaped trichome contains hundreds of compounds like cannabinoids, terpenes, and flavonoids- a secondary metabolite that pigments plants. The resins deter pests by their bitter taste and strong aroma, which is undesirable by most insects and animals. The non-glandular variety, however, serves to protect the plant from pests. The trichomes are coveted by growers for their resin, therefore the females are prized.


Males


Male plants serve the purpose of providing the pollen for fertilizing female plants and they are perfect for fiber and seed crops. However, in CBD flower production, the males are not wanted. The presence of a single male amongst mature females spells disaster for the cultivator because the harvested flowers will have a very low cannabinoid content and contain a many seeds. In terms of breeding though, males are sought after. They may offer traits such as pest and disease resistance and climate resilience.


Fiber and seed growers need to be mindful of their neighbors’ crops because they could ruin an entire flower crop. Hemp pollen can drift from 10 miles up to 30 miles and potentially travel further than that depending on the strength of the wind and location of the crop (Aschner, 2020). It is interesting to note that males do contain some cannabinoids and terpenes because they possess trichomes like their counterparts, though not in the same concentration and abundance. Another interesting point is that within fiber cultivation, the two sexes will generate different fiber qualities, for instance, the females produce coarse and very strong fibers, whereas the males produce softer fibers which are more suited to the textile industry.


Males - Stamen


Hermaphrodites


The term “hermaphrodite” is given to a female plant when it exhibits both male and female parts. This can happen for a number of reasons. The genetics of the cultivar (cultivated variety) could be prone to developing male parts, so careful seed selection is crucial. It is essential to research and purchase from a reputable seed company. Be wary of feminized seeds because they can still yield male plants or they can produce hermaphrodites. The environment plays a significant role as well. It shows up as stress, which will make a female plant generate male traits in order to pollinate itself and complete its life cycle sooner. Consider it the plant’s insurance policy. Please note, this issue is only a nuisance in flower cultivation.


A hermaphrodite plant featuring stamens and stigmas


A few examples of environmental stressors include:

  • Temperatures - too high or too cold -For most of their life cycle these plants thrive in a climate that is between 70-85℉, and at the end prefer cooler temperatures of 50-70℉ -Cold temperatures will stunt growth and possibly damage tissues -Hot temperatures will produce airy flowers and can cause stem elongation


  • Light - not enough or too much -For outdoor crops → these plants desire full sun, but this is less of an issue for growers, unless the chosen genetics are not suited for the climate -For indoor crops → in their vegetative life cycle they require 18 hours of light and 6 hours of darkness; in their flowering life cycle they require 12 hours of light and 12 hours of darkness -Light disruption is more likely to occur in an indoor facility


  • Water - too much or too little -Depending on the soil composition will determine drainage; the best composition will be loose, aerated soil and contains compost -Roots do not want to be submerged in water -Cannabis needs a lot of water at certain points of its life cycle and, depending on an outdoor crop, the weather dictates watering amounts (hot and sunny days requires more water, rainy days requires less watering)


  • Overly ripened flowers - past the point of harvesting -As a last-ditch effort to be fertilized, females will develop male parts in order to complete their life cycle; sometimes referred to as rodelization


  • Pests and diseases -Can wreak havoc on a plant if overrun with the pest or disease, ultimately lowers the plant’s resilience and inhibit the ability to produce healthy flowers


Key Takeaways


There are some important lessons to take away from this anatomy breakdown.

One should understand:

  • Why CBD cultivation is exclusive to females only

  • How and when to look male and female pre-flowers

  • The importance of trichomes

  • How hermaphrodites occur and why they are nuisances to CBD cultivation

  • Why the industry needs both sexes to accomplish the following things: -Breeding for flower genetics, as well as for fiber and seed genetics -Cultivating fiber and seed crops


References


Andre, C. M., Hausman, J. F., & Guerriero, G. (2016). Cannabis sativa: The Plant of the Thousand and One Molecules. Frontiers in plant science, 7, 19. https://doi.org/10.3389/fpls.2016.00019


Aschner, N. (2020). Pollen Drift: Is Your Business Facing Legal Risks? Retrieved from https://www.hempgrower.com/article/drifting-into-new-legal-territory/


DeDecker, J. (2019). Weighing the risk of cannabis cross-pollination. Retrieved from https://www.canr.msu.edu/news/weighing-the-risk-of-cannabis-cross-pollination


Gonçalves, J., Rosado, T., Soares, S., Simão, A. Y., Caramelo, D., Luís, ., Fernández, N., Barroso, M., Gallardo, E., & Duarte, A. P. (2019). Cannabis and Its Secondary Metabolites: Their Use as Therapeutic Drugs, Toxicological Aspects, and Analytical Determination. Medicines (Basel, Switzerland), 6(1), 31. https://doi.org/10.3390/medicines6010031


Hennings, T. (2019). 4 ways to make use of male cannabis plants. Retrieved from https://www.leafly.com/news/growing/4-ways-to-make-use-of-male-cannabis-plants


Rosenthal, E. (2019). Environmental Stresses. In Marijuana Garden Saver: A Field Guide to Identifying and Correcting Cannabis Problems (pp. 157–189). Piedmont, CA: Quick American.

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