Cannabis Genetics Guide: Phenotypes, Lineage, and More

When it comes to cannabis genetics and the ‘Marijuana Family Tree,’ we’ve unfortunately been left to the devices of anecdotal information over much of the last half-century. In other words, there is very little reliable scientific data as to where the thousands of present-day cannabis strains came from, and what exactly their specific genetic traits consist of.

In fact, as we learn more and more about the historic genetic lineage of cannabis, we (and by “we” I am referring to scientists who actually study this stuff), are seeing an increasing likelihood that all forms of marijuana belong to a single species: Cannabis sativa L.

Of course, that’s not to say there are dozens (if not hundreds or even thousands) of different ways in which marijuana can “present itself” – some plants are short and bushy and provide calming, sedative effects, while other plants rocket towards the sky and resemble more of a beanstalk than a marijuana plant.

In this article, we discuss as comprehensively (and painlessly) as possible everything we know about cannabis genetics, including the historical origins of the plant, what the real differences between an indica and sativa are, and where all of these thousands of different “strains” with their ridiculous names came from. Let’s get started.

A Basic Introduction to Marijuana Genetics

Speak to any “experienced” cannabis grower, and he or she will probably be more than happy to lay down an absurd amount of information regarding distinct cultivars, specific cannabinoid profiles (levels of THC and CBD), terpene content, and so on. Unfortunately, most of what they (think) they know has been based on decades of flawed, unfounded “data” that’s simply been passed down through generations of anecdotal bullshit.

Realistically, all forms of cannabis probably belong to a single species (C. sativa L), with the vast amounts of variation in terms of appearance and physiological effects simply due to individual gene expression (or lack thereof).

Think of it this way. There are over seven billion people living here on earth – how many different “arrangements” exist in terms of our physical appearance? What about our mental and behavioral differences? Pretty much an endless amount, right?

Even though we as humans all belong to a single species (H. sapiens), we can be incredibly different in terms of the way we look, the way we think, the way we feel, and the way we act as individuals. Cannabis is no different. The traits of every marijuana plant out there are dependent upon specific genes that are expressed on microscopic little structures called chromosomes.

In terms of simple marijuana genetics, cannabis has 20 different chromosomes (for reference, humans have 46) with potentially hundreds of different genes existing on each one. Just like human beings, marijuana receives an individual chromosome from a single mother and a single father (cannabis has both male and female plants).

When these chromosomes combine, a unique arrangement of expressed and non-expressed genes is formed. This is why – even in a crop that’s been pollinated by a single male plant with known genetics – you can get offspring that possess wildly different phenotypes and cannabinoid profiles.

Speaking of ‘phenotypes,’ let’s take a brief minute to discuss some of the most relevant terms in the world of cannabis genetics and taxonomic lineage.

Cannabis Genetics 101: Know Your Terminology

Hopefully, at some point in your academic career, you’ve taken an ‘intro to genetics’ course or at least heard of a few of the following phrases in a middle or high school biology class. If you haven’t, however, fear not — we’re here to help. Here are several of the most common terms you’ll come across when discussing marijuana genetics.


Cannabis genetics termDefinition
GeneA specific sequence of DNA that codes for a specific trait in the cannabis plant
AlleleA variation of a single gene (cannabis plants have two alleles for each gene – one from each parent)
PhenotypeVisual/observable characteristics of the cannabis plant (plant height, flower shape, bud appearance, aroma, etc)
GenotypeThe entire set of genes in a cannabis plant
LandraceMarijuana strains that grow naturally in the wild in a specific geographic region on earth
HeirloomMarijuana strains that were historically planted and harvested in crops cultivated by humans (unlike landrace strains, heirlooms do not grow in the wild)
CrossbreedThe result of breeding marijuana with one set of genetic traits with another that has a different set of genetic traits
F1 generationThe resulting plants from a breed of two plants with different genotypes
PolyhybridsA crossbreed of two hybrid cannabis plants with distinct genotypes
BackcrossThe offspring of a hybrid strain that has been bred with the original parent plant
SelfingThe resulting offspring when a female plant self-pollinates (under stress, female marijuana plants can develop male sex characteristics and pollinate themselves)

Ok, so on to the actual lineage of cannabis genetics and the historical marijuana family tree. Where did it all begin? How do we trace the thousands of strains that exist today back to a single breed of marijuana? Or better yet, would this even be remotely possible?

From a purely scientific perspective, it would indeed be impossible to create a “marijuana family tree” and trace all of the modern-day strains back to a single origin. We could formulate logical guesses, sure, but there is absolutely no way anyone could build an accurate phylogenetic tree on the genetic history of cannabis.

First, we would have to know what the original landrace strain was that all other strains came from. We do not know this, and we never will. In fact, we don’t even know where the first marijuana strain originated from, or when it was first cultivated by humans and crossbred into F1 hybrids.

Fortunately, thanks to the combination of science and history we can come up with some pretty accurate guesses. As you’ll see here shortly, it would appear that the very first cannabis genetics and phenotypes on earth appeared somewhere in Asia — probably in the modern day Hindu Kush mountains.

Tracing the Origins of Marijuana Genetics

Contemporary research has suggested three possible origins of cannabis that gave rise to the plethora of marijuana genetics that we enjoy today. In other words, one of the following three locations was the very first spot on earth where a marijuana plant first spouted out of the soil and grew in the wild (credit to AlchimiaWeb for the references):

  • In China along the banks of the Yangtze River
  • In the Takla Makan desert of central Asia
  • Amidst the fertile valleys of the Himalayan and Hindu Kush mountain ranges of South Asia

In terms of general aesthetics, most of us would probably choose to believe that the third option (the Hindu Kush mountains) is the spiritual home of all forms of modern-day marijuana. Of course, we will never know for sure.

What we do know is that the first marijuana plants and cannabis genetics appeared on earth and grew in the wild somewhere in Asia. From there, it was eventually cultivated by humans for various purposes, including medicinal and therapeutic purposes.

Archaeological evidence has suggested that some strain of cannabis genetics was being cultivated in China as early as 8,000 BC. Of course, China was a powerful empire at this point in history, so it is not beyond the realm of possibility that Chinese explorers could have brought the plant back from some other far-off land in central or southern Asia.

Either way, aside from evidence that cannabis was being cultivated as early as 8,000 BC, we also have historical evidence (thanks to the pharmacopoeia of Shen Nung) that cannabis was being used as a medicine as early as 2730 BC).

From China, it would appear that human cannabis cultivation had spread to the middle east and Russia by 2,000 BC. From there, it appears that some cultivars had “spread” to civilized Africa by 700 AD.

In terms of cannabis genetics in Central and South America, we have evidence that Spanish explorers brought the plant to present-day Chile and Peru during the mid-16th century. Cannabis domestication then spread to North American throughout the 17th century, where hemp played a crucial role in the success of the first American colonies.

But that’s enough regarding the history of cannabis genetics — what about actual cannabis genetics? Where on earth did marijuana come from? What plants is it related to on an evolutionary level? Let’s have a look…

The Marijuana Family Tree: A Complex Evolution of Cannabis Genetics

Depending on where you look, you can find various taxonomic trees that trace the evolutionary origins of cannabis back to different ancestors. Thankfully, we can rely on the work of Carl Linnaeus to formulate the most accurate estimation of where marijuana evolved from.

Linnaeus identified the taxonomic genus and species of marijuana back in 1753, formally identifying the plant as Cannabis sativa L. (‘Cannabis‘ refers to the genus, while ‘sativa L.‘ refers to the species). To refresh your memory, here is a general rundown of the seven major classes of taxonomic classification: Kingdom, Phylum, Class, Order, Family, Genus, Species.

According to the Linnaean classification system (which attempts to identify and organize the evolutionary history of all living things on earth), cannabis genetics are organized in the following manner:


KingdomPlantae (all living plants)
DivisionMagnoliophyta (all flowering plants)
ClassMagnoliopsida (all dicotyledons)
OrderRosales (previously Urticales)
SpeciesC. sativa L

Using this cannabis genetics classification system, we can accurately suggest that marijuana is most closely related (from an evolutionary standpoint) to the following plants: Hops, Hackberry, Evergreen trees, and Sandalwood.

Surprised? Indeed, marijuana genetics and evolution is a vastly complex subject, as it is with all living things on earth. That said, this is the information that we have to go off of, and thus this is as close as possible that we can determine the accurate identification of cannabis genetics.

In terms of the massive amount of strains that exist today, we can likely trace all of them (if we go back far enough) to a single cultivar belonging to the C. sativa L species. In other words, the whole notion of “indicas” and sativas is likely bullshit. Yep, we said it.

Cannabis Genetics and the “Indica/Sativa Myth”

When we say that the existence of a distinct species of cannabis called ‘indica’ is complete and utter bullshit, we’re certainly not implying that different (and highly unique) varieties of cannabis exist — they most certainly do.

We have marijuana strains that make us energized, as well as strains that make us calm and sedated. We have plants that are 18 feet tall and barely flower at all, and we have plants that barely reach four feet off the ground and produce nuggets the size of a pitbull’s head.

However, this doesn’t mean there is a separate species of cannabis called ‘sativa.’ In fact, Dr. Alisha Holloway has purported in an article for Medium that narrow-leafed cultivars of pot (traditional ‘sativas’) seem to be on the whole energizing, while shorter, broad-leafed plants (traditional ‘indicas’) seem to be more energizing and uplifting.

If you know anything about the historic indica vs sativa debate, you’ll know that this is pretty much the exact opposite of what we’ve “learned” over generations of anecdotal reports. In other words, Dr. Holloway has implied that there is only one way to identify “true” cannabis genetics – and that is to accurately identify a specific cultivar’s genotype and chemotype.

Unfortunately, we don’t have a genetic database of cannabis to be able to do this. As such, breeders all across the world have for decades been getting away with popping off F1 or F2 generations of plants, giving them a crazy-ass “strain name,” and claiming that they’re loaded with consistent, identifiable traits and phenotypes.

This is where the ‘utter bullshit’ part of the whole thing comes in. Case in point, all you have to do is buy a couple strains of “Blue Dream” from various dispensaries across the US, and you’ll realize pretty quickly that each of them has their own unique appearance and mental/physical effects.

This all goes back to the comparison that we made earlier in the article; as human beings, we all belong to one species: H. sapiens. However, this certainly doesn’t mean we can accurately predict our appearance or general behavior as individuals.

Final Thoughts on Cannabis Genetics and the Marijuana Family Tree

To wrap things up, we’d like to highlight another assertion made by Dr. Holloway in regard to cannabis genetics. She said that by understanding cannabis exists as a single species, we recognize the fact that a “universe of genetic diversity” exists and that we can’t accurately identify the effects or appearance (or even the cannabinoid profile) of a particular cultivar based on strain name alone.

She suggests that all marijuana genetics should belong to the single species Cannabis sativa L, and that the “relationships between different cultivars” should be based solely on genotype.

We hope that this article on cannabis genetics has been helpful, interesting, and informative and that it in some way has helped to shed some light on this intriguingly complex topic. And if it hasn’t, well, we apologize.

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