Weed, pot, hemp, marijuana, Mary Jane, dope... Regardless of name, we are all quite familiar with the plants in the genus Cannabis, at least in the context of their relationship to humans. With Colorado and now Washington being the first states in America to legalize its recreational use and plenty more states slated to do the same, the genus Cannabis is as hot of a topic today as it has ever been.
Admittedly a lot of what is said about these plants is based in misinformation and senseless hysteria, however, there is no denying just how significant this genus has been to humans over recorded history. Despite the celebrity status, it is staggering to realize just how little people know about the ecology of these plants. When you strip away all of the anthropogenic uses and their maligned reputation, you will find a very interesting natural history indeed.
Originally native to the Caucasus region of eastern Europe, India, and Iran, as well as parts of Africa, there are purported to be 3 species in the genus Cannabis, though there is some debate over this. In the wild they are said to grow in open, disturbed habitats. This lack of specificity when it comes to habitat has allowed Cannabis to attain a near global distribution. It can now be found growing in mild climates throughout the world and can readily escape cultivation when conditions are right.
Cannabis was once placed in the nettle family and then the mulberry family, but DNA analysis has since moved it into its own family, Cannabaceae, of which hops (Humulus) and hackberries (Celtis) also belong. All species of Cannabis are wind pollinated annuals. Most of the time, plants are dioecious, meaning individuals are either male or female, however, it isn't uncommon for some individuals to be monoecious (male and female parts on the same plant). All 3 species will readily hybridize with each other, a fact that has been widely utilized by breeders. It is the female flowers that are most coveted for consumption as they contain the highest amounts of the chemical THC.
There are many hypotheses as to what function THC has for the plant. It is a secondary metabolite, meaning it does not serve a direct role in the growth, development, or reproduction. It is produced from glandular trichomes that can be found in the greatest abundance on the female flowers. Research indicates that THC plays a multifaceted role in protecting the plant from fungi and microbial infection as well as deterring herbivory. Recently it has been found that THC has high UV-B absorption properties, leading some to believe it may also protect the plant from sun exposure.
Whether you venerate this genus or despise it, you cannot deny the fact that this is one group of plants that has been quite serendipitous in its evolutionary trajectory. The wide array of uses attributed to the genus Cannabis has lead to near global dominance. Plants like this really make you question which species has the upper hand. Above all else, I would only ask that people on both sides of the argument approach this subject with an open mind. At least here in America, I think we are entering a new era with these plants.