Why do marijuana plants produce THC?

Delta-9-Tetrahydrocannabinol (THC) is a type of ​phytocannabinoid​, a chemical compound produced by plants. THC is famous for its psychoactive effects on humans and other animals when ingested in the right quantities. Plants that contain THC include cannabis (​Cannabis sativa​) and, at low levels, hemp (​Cannabis sativa​ ssp. ​sativa​).

THC and CBD are the ingredients of marijuana. They are known for their medical benefits.

THC and CBD are different in respect to their effect on the body and mind. THC is psychoactive and gives the feeling of high when consumed on the other hand CBD is non-psychoactive and have a calming effect.

THC is produced by the cannabis plant as a defensive measure against herbivores and omnivores, Cannabis produces THC and other chemicals, called cannabinoids, which are mainly used as repellents for grazing animals such as birds, horses and pikas. Over millions of years, it has evolved higher and higher concentrations of these chemicals. Over millions of years, fewer and fewer animals eat it, because they either don’t like the feeling after it, or in some cases, they are directly poisoned by it and avoid eating it at all costs.

However, cannabis is not the only plant that makes cannabinoids. THC is unique to it

THC specifically may protect the plant from ultraviolet light. Researchers at the University of Maryland exposed cannabis plants from different areas of the world to UVB rays through irradiation and found that they produced more THC than those that were not exposed, suggesting a protective function.

So far, marijuana and hemp are the only plants that contain THC; hemp contains 0.3% or less while marijuana contains more than 0.3%. However, other plants also contain cannabinoids such as Coneflower, Electric Daisy, and Liverwort.

In the mid-1970s, the average THC content found in confiscated cannabis samples was about 1.3%. In the late 1990s, this figure rose to 3.8%. In 2014, the average was 12.2%, while today, you can find up to 32% of strains.

THC concentrations have been steadily increasing and are likely to continue to increase due to selective breeding, better planting techniques and greater attention to cannabis cultivation. They will eventually reach the upper limit, but with the invention of concentrates, tinctures and edible foods, THC content in some products can reach 100%. However, in the marijuana plant itself, we have basically reached the limit of marijuana carrying. 35% is the upper limit of THC level of strains. Exceeding this upper limit requires direct genetic engineering or concentration. Similarly, the upper limit of CBD effectiveness is about 25%.

Unfortunately, any more than .3% THC, automatically makes it illegal to purchase in many states. THC oil cartridges for vaping contains as much as 80% THC.