Cannabis Botany 101

Cannabis sativa L. has served us well for thousands of years. Since ancient times various parts of the Cannabis plant have provided food, medicine, clothing, paper, fuel, building materials and more to humanity. Here is an overview of the plant, and its genetic background.

Cannabis was a widely prescribed folk medicine in Europe and the Americas prior to the age of synthetic pharmaceuticals and still figures in the religious practices of some cultures. In fact, from around 2000 BCE until 1883 Cannabis was amongst the largest agricultural crops on the planet, and ranked highly in medications globally during this period. Around 1910 these traditional uses came under political pressure initiated by the American, British, Egyptian and South African governments.

The Cannabis family

Cannabis botany 101

Today the Cannabis family of plants can be separated into four main groups: Cannabis Sativa, Cannabis Indica, Cannabis Ruderalis, and hybrids of the previous three. Ruderalis plants do not contain noticeable amounts of THC and will not impart any drug effect.

A debate exists regarding genetic distinctions of these groups but these are the terms commonly used within the community, and therefore the terms we will focus on using in this Cannabis botany 101 article. 

Generally speaking, Sativa plants are taller and have more space between the leaf intersections (internodes) due to their origins in tropic, sub-tropic and equatorial climates. Their leaves tend to be thinner and slightly lighter green than their Indica or Afghan counterparts, which originate instead in central Asia. In fact, many historians, botanists and anthropologists believe that Central Asia between Kazakhstan and Afghanistan is the birthplace of weed. These cold mountainous regions produce short, compact bushy plants with wide and often very dark green leaves.

Only the female Cannabis plants are consumed, as their flowers produce trichomes or resin glands containing chemical compounds responsible for the drug effect of the plant. Some of these cannabinoids are actually non-psychoactive, however as precursor drugs their presence is necessary for intoxication to take place. There are also male Cannabis plants, which closely resemble mature hop plants. Cannabis is also distantly related to the nettle plant.


There are a few plants that may cause confusion in a greenhouse or grow room; these are known as hermaphrodites and inter-sex plants. Hermaphrodites contain both genders on the same plant and may be female- or male- dominant. Inter-sex plants contain an equal mix of both genders. All mixed gender plants should be disposed when growing for consumable cannabis, as they contain unstable breeding information (genetics) and will cause seeds to appear in the crop, thereby changing the drug content.

A debate exists regarding genetic distinctions of these groups but these are the terms commonly used within the community. 

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Frequently asked questions

Is it hard to grow Cannabis?

Cannabis is an easy plant to grow. It is not called a weed for no reason. Refer to our Basic growing guide for more information.

What Cannabis seeds should I choose?

This is a difficult question to answer. Seeds come in different forms: regular seeds producing both male and female plats, feminised seeds, and autoflowering seeds. Each has its advantages and disadvantages. Choosing the ones best suited to you depends on what your are looking for from your cannabis plant and your level of experience.

How long does it take to grow Cannabis?

This depends on the Cannabis variety you are growing and its environment. Life cycles can vary from two and a half months for autoflowering varieties to more than 18 months for certain sativa varieties.