Hemp and marijuana are not different plants. Both are Cannabis sativa, bred over thousands of years for different purposes: hemp for fibre and seed, and drug varieties for THC-rich flowers.12 CBD comes mainly from the resin on the female flowers, and hemp varieties tend to make more of it.34
What kind of plant is cannabis?
Cannabis is a fast-growing herb.3 It belongs to the plant family Cannabaceae. Its closest relative is hops (Humulus), the plant used to flavour beer.1
Fossil pollen points to the north-eastern Tibetan Plateau as the place where cannabis first arose.1 A 2021 genetic study of plants from around the world concluded that people first domesticated it in East Asia about 12,000 years ago, and that the lines bred for fibre and the lines bred as a drug split apart around 4,000 years ago.2
Is cannabis one species or three?
You will often see three names: Cannabis sativa, Cannabis indica and Cannabis ruderalis. Botanists have argued about this for a long time. A 2018 review of the plant’s classification concluded that they are best treated as varieties of a single species, Cannabis sativa.1
What is the difference between hemp and marijuana?
The difference is in what the plant has been bred to produce.
| Hemp | Drug-type cannabis (“marijuana”) | |
|---|---|---|
| Bred for | Fibre and seed3 | Flowers rich in THC4 |
| Main cannabinoid | CBD (as CBDA)3 | THC (as THCA)3 |
| THC content | Low. United States law, for example, defines hemp as cannabis with no more than 0.3% THC by dry weight5 | High. THC exceeds CBD in the flowers4 |
“Marijuana” is an informal word with no botanical meaning. “Hemp” is partly a legal term: each country sets its own THC threshold. Australia’s rules are covered on industrial hemp in Australia.
A plant’s genes largely decide which cannabinoid it makes. Both THC and CBD start from the same parent compound, CBGA. One enzyme converts it to the raw form of THC, another to the raw form of CBD.4 The 2021 genetic study found that most drug varieties carry a working gene for the THC enzyme and broken copies of the CBD enzyme gene. Most hemp plants are the reverse.2
Growing conditions also play a part. One study of industrial hemp found that CBD content rose with soil and air temperature and fell with rainfall.4
Which parts of the plant contain CBD?
| Plant part | Cannabinoid content | Main use |
|---|---|---|
| Female flowers | Highest. Cannabinoids collect in resin glands (trichomes) that occur mostly here3 | Source of CBD and THC |
| Leaves | Lower. Highest in the upper leaves, and falling as leaves age3 | Minor source |
| Seeds | The kernel has only trace amounts. THC found on seeds is mainly on the outer coat, probably from contact with resin3 | Food and seed oil |
| Stalk | Grown for fibre, not cannabinoids | Long outer fibres for textiles, woody core for animal bedding and building material3 |
| Roots | Low quantities only3 | Not a practical source of CBD |
This is why hemp seed oil and CBD oil are different products. One is pressed from seeds that contain almost no cannabinoids. The other is made from flower extract. See CBD oil vs hemp seed oil and hemp foods in Australia.
How does the plant make CBD?
The plant does not make CBD directly. The steps are:4
- The plant makes CBGA, the parent compound of the main cannabinoids.
- An enzyme converts CBGA into CBDA (cannabidiolic acid).
- CBDA loses a small part of its structure when it is exposed to heat, light or simply time. What is left is CBD. Chemists call this decarboxylation.
Some of this happens in the plant, but much more happens when the harvested material is heated.3 This is why fresh, unheated plant material contains mostly the acid forms. See CBG, CBN, CBC and CBDA and how CBD is extracted and made.
What else is in the plant?
A great deal. More than 540 compounds have been described in hemp.3 They include:
- Cannabinoids. More than 90 have been reported, although some are breakdown products of others.3
- Terpenes. More than 100 have been identified in cannabis. They give each variety its smell.3 See terpenes.
- Flavonoids. About 20 have been identified.3
The idea that these compounds work better together than apart is called the entourage effect. It is a hypothesis, not an established fact.
Do “sativa” and “indica” labels mean anything?
Not much. Cannabis products are often sold as “sativa” (said to be uplifting) or “indica” (said to be relaxing). The botanical review mentioned above found that these everyday labels do not match the plants’ formal names, and that widespread cross-breeding “has rendered their distinctions almost meaningless”. One well-known variety won a “best sativa” award in 1999 and a “best indica” award four years later.1
What matters is the measured content: how much CBD, how much THC and what else. That is what a certificate of analysis shows.
Is CBD always made from plants?
No. CBD can also be made in a laboratory by chemical synthesis.4 The registered CBD medicine Epidyolex is a purified, plant-derived CBD.4 Plant-derived and synthetic CBD are the same molecule.
Can I grow cannabis for CBD in Australia?
Knowing the botany does not change the law. In Australia you need a prescription to use a CBD medicine.6 The rules on growing and possession are covered on Is CBD legal in Australia? and cannabis legalisation in Australia.
Footnotes
-
McPartland JM. Cannabis systematics at the levels of family, genus, and species. Cannabis and Cannabinoid Research, 2018. https://pmc.ncbi.nlm.nih.gov/articles/PMC6225593/ ↩ ↩2 ↩3 ↩4 ↩5
-
Ren G, et al. Large-scale whole-genome resequencing unravels the domestication history of Cannabis sativa. Science Advances, 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8284894/ ↩ ↩2 ↩3
-
Andre CM, Hausman JF, Guerriero G. Cannabis sativa: the plant of the thousand and one molecules. Frontiers in Plant Science, 2016. https://www.frontiersin.org/articles/10.3389/fpls.2016.00019/full ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8 ↩9 ↩10 ↩11 ↩12 ↩13 ↩14 ↩15
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World Health Organization, Expert Committee on Drug Dependence. Cannabidiol (CBD) critical review report, 2018. https://cdn.who.int/media/docs/default-source/controlled-substances/whocbdreportmay2018-2.pdf ↩ ↩2 ↩3 ↩4 ↩5 ↩6 ↩7 ↩8
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US Food and Drug Administration. FDA regulation of cannabis and cannabis-derived products, including cannabidiol (CBD). https://www.fda.gov/news-events/public-health-focus/fda-regulation-cannabis-and-cannabis-derived-products-including-cannabidiol-cbd ↩
-
healthdirect Australia. Medicinal cannabis, last reviewed February 2026. https://www.healthdirect.gov.au/medicinal-cannabis ↩
Common questions
Is hemp the same plant as marijuana?
Yes, they are the same species. Hemp is the name for varieties grown for fibre and seed, which make very little THC. Marijuana is an informal name for varieties grown for their THC-rich flowers. Laws separate them using a THC threshold.
Which part of the cannabis plant has the most CBD?
The female flowers. Cannabinoids are made and stored in tiny resin glands called trichomes, which are concentrated on the flowers. Leaves have less, roots have very little, and the seed kernel has only trace amounts.
Does hemp seed oil contain CBD?
Only traces, if any. The seed kernel makes almost no cannabinoids. Small amounts can end up on the outside of the seed from contact with flower resin. Hemp seed oil is a food, not a CBD product.
Is CBD from hemp different from CBD from marijuana?
No. CBD is the same molecule whichever variety it comes from, and it is the same again when made in a laboratory. What differs between products is what else is in the extract, especially how much THC.
This page is general information, not medical or legal advice. Laws and evidence change; we show the date we last checked the facts at the top of every page. Talk to your doctor or pharmacist before starting, stopping or changing any medicine.
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