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by Dr. Pierre Milot, PhD.
The Genetics of Cannabis
Cannabis is believed to be one of the oldest domesticated crops. Throughout history, humans have grown different varieties of cannabis for industrial and medical uses.
Tall, sturdy plants were grown by early civilizations to make a variety of foods, oils and textiles, such as rope and fabrics. These plants were bred with other plants with the same characteristics, leading to the type of cannabis we now know as hemp.
Other plants were recognized for being psychoactive and were bred selectively for medical and religious purposes. This led to unique varieties of cannabis that we now know as marijuana.
According to Dan Sutton of Tantulus Labs, a Canadian company that specializes in cannabis cultivation technology, “the core agricultural differences between medical cannabis and hemp are largely in their genetic parentage and cultivation environment.”
In fact, scientists believe the early separation of the cannabis gene pool led to two distinct types of cannabis plants. The two species (or subspecies) of cannabis are known as Cannabis Indica and Cannabis sativa.
Cannabis plants contain unique compounds called cannabinoids. Current research has revealed over 100 different cannabinoids so far, but THC is the most well known. THC is credited with causing the marijuana high.
While marijuana plants contain high levels of THC, hemp contains very little or none at all of the psychoactive chemical. This single difference is what most rely on to distinguish hemp from marijuana. For example, countries like Canada have set the maximum THC content of hemp at 0.3 percent. Any cannabis with higher THC levels is considered marijuana instead.
In comparison, medical marijuana produces anywhere between 5-20 percent THC on average, with prize strains tipping the scale at 25-30 percent THC.
Hemp and marijuana plants contain another important cannabinoid: CBD. Hemp plants produce more CBD than THC, while marijuana produces more THC than CBD. Interestingly, research has shown that CBD acts to reduce the psychoactive effects of THC, separating hemp further from marijuana.
Hemp and marijuana are grown for different uses, and therefore require different growing conditions.
Medical cannabis has been selectively bred over generations, and its characteristics are optimized in its cultivation environment to produce female flowering plants that yield budding flowers at the flowering stage of their life cycle,
In contrast, hemp plants are primarily male, without representing flowering buds at any stage in their life cycle. Instead, centuries of selective breeding have resulted in relatively low concentrations of THC, and tall, fast growing plants optimized for higher stalk harvests.
* Achieving maximum THC levels in marijuana is tricky and requires close attention to grow-room conditions. Marijuana growers usually aim to maintain stable light, temperature, humidity, CO2 and oxygen levels, among other things.
On the other hand, hemp is usually grown outdoors to maximize its size and yield and less attention is paid to individual plants.
A Bit About the Anatomy of the Marijuana Plant
Most people know that THC is only present in the female cannabis plant, because this is the one that produces those resinous flowers that are able to provide the high that so many marijuana consumers desire. On the other hand, the male cannabis plant, which is also known by some as hemp, might not have any THC present, but it does contain some CBD. Both the female and male cannabis plants have a source of CBD, so they both make suitable options for cannabidiol oil extraction and processing.
* In addition to being female and male, cannabis plants can also be hermaphroditic (a.k.a. both!). Pretty neat right? Hermaphrodite plants are capable of pollinating themselves, because they contain both female and male sex organs. This is a nuisance though for marijuana growers, because it means their final product will be filled with seeds and the hermaphrodite genetics can be passed down onto other generations, which defeats the purpose of having feminized seeds. To ensure a female plant, either specifically bred feminized seeds can be purchased, or clones of a female cannabis plant.
The structure of a female cannabis plant, also known as the marijuana plant, is typically built up of a stem with roots that dig deep into the earth, with fan leaves and sometimes colas that stick out in between some of the fan/water leaves. These colas are a mass collection of the buds, which are the flowers and the part of the plant that can get you high.
* These buds contain sugar leaves, which are coated with those crystal-appearing trichomes (the component that directly contains the THC and shown in the last picture). Additionally, pistils and stigmas are those tiny, usually orange hairs mixed amongst the sugar leaves. Lastly, there are calyxes and bracts, which also contain potent quantities of cannabinoids.
Dr. Pierre Milot, PhD., PhD. (tc)
Certified Medical Cannabis Counselor