# What is the difference between hemp and marijuana?

> Hemp and marijuana are the same species, Cannabis sativa. The difference is chemistry, breeding and law: hemp is cannabis grown for fibre, seed or low-THC flower, defined in many laws as no more than 0.3% THC by dry weight, while marijuana is drug-type cannabis bred for high THC. The two groups are genetically distinct populations, and many fibre hemps are bred monoecious.

- Canonical: https://genetixbay.com/knowledge/answers/hemp-vs-marijuana.html
- Topic: Basics · Type: Definition
- Evidence: Established · Status: Draft: awaiting expert review
- Full article: [Cannabis plant biology: the parts and what they do](https://genetixbay.com/knowledge/basics/cannabis-plant-biology.md)
- Also asked as: Hemp vs weed | Is hemp the same plant as cannabis? | Hemp vs cannabis difference | Is hemp just low-THC cannabis?
- Updated: 2026-10-31 · Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay Knowledge Base (genetixbay.com/knowledge)"

## Short answer

[Hemp](https://genetixbay.com/knowledge/glossary/hemp.md) and marijuana are the same species, *[Cannabis sativa](https://genetixbay.com/knowledge/glossary/cannabis-sativa.md)*. Hemp is cannabis bred and grown for fibre, seed or low-THC flower, and many laws define it as no more than 0.3% [THC](https://genetixbay.com/knowledge/glossary/thc.md) by [dry weight](https://genetixbay.com/knowledge/glossary/dry-weight.md). Marijuana is drug-type cannabis bred for high THC. *Established* botany; the legal line varies by place.

## Why

One species, two uses. Most botanists treat all cultivated cannabis as *Cannabis sativa*, with fibre, seed and drug types shaped by thousands of years of human selection [3].

The 0.3% line is a convention. Small and Cronquist proposed 0.3% THC in dry flowering [tops](https://genetixbay.com/knowledge/glossary/top-shelf.md) as a practical boundary between the groups in 1976 [1]. Many laws later adopted it, with differences in which THC is counted (THC only, or total THC including [THCA](https://genetixbay.com/knowledge/glossary/thca.md)) and how samples are taken.

The groups are genetically distinct. Genome-wide markers separated hemp from marijuana as different populations [2]. Chemistry differs too: drug types are mostly THC-dominant, many hemps CBD-dominant or low in all [cannabinoids](https://genetixbay.com/knowledge/glossary/cannabinoid.md) [4].

Breeding goals differ. Fibre hemp is bred tall, dense-sown and often [monoecious](https://genetixbay.com/knowledge/glossary/monoecious.md), with both sexes on one plant. Drug-type cannabis is grown as seedless ([sinsemilla](https://genetixbay.com/knowledge/glossary/sinsemilla.md)) females for resin.

## The numbers

| | Hemp | Drug-type cannabis |
|---|---|---|
| Species | *Cannabis sativa* | *Cannabis sativa* |
| Legal THC limit (many places) | ≤ 0.3% by dry weight | None, or licensed |
| Bred for | Fibre, grain, oil, [CBD](https://genetixbay.com/knowledge/glossary/cbd.md) | THC-rich resin |
| Typical [chemotype](https://genetixbay.com/knowledge/glossary/chemotype.md) | CBD-dominant or low | THC-dominant |
| Sex system | Often monoecious (fibre types) | [Dioecious](https://genetixbay.com/knowledge/glossary/dioecious.md); females grown |

## What to do

1. Treat "hemp" as a legal and use category, not a separate plant.
2. Growing hemp? Rules, licences and testing vary; check your local rules.
3. Growing CBD flower? Test before harvest; CBD-dominant plants still make some THC.
4. Keep hemp pollen away from a sinsemilla grow.

## Common mistakes

- Thinking hemp and marijuana are different species.
- Assuming "hemp" seed will always test under the limit.
- Assuming the 0.3% rule means the same thing everywhere.

## Related

- Full article: [Cannabis plant biology](https://genetixbay.com/knowledge/basics/cannabis-plant-biology.md)
- Answers: [THC vs CBD plants](https://genetixbay.com/knowledge/answers/thc-vs-cbd-plants.md) · [strain vs cultivar](https://genetixbay.com/knowledge/answers/strain-vs-cultivar.md)
- Article: [Indica, sativa and ruderalis](https://genetixbay.com/knowledge/genetics-history/indica-sativa-ruderalis.md)
- Terms: [hemp](https://genetixbay.com/knowledge/glossary/hemp.md) · [marijuana](https://genetixbay.com/knowledge/glossary/marijuana.md) · [monoecious](https://genetixbay.com/knowledge/glossary/monoecious.md)

## Follow-up questions

**Where does the 0.3% THC hemp limit come from?** The 0.3% THC line between hemp and drug-type cannabis traces to a 1976 taxonomy by Small and Cronquist, who used 0.3% THC in dry flowering tops as a practical boundary between the two groups. Laws in the US, Canada and the EU later adopted 0.3%, though they differ on which THC counts and how samples are taken. Check your local rules.

**Can hemp get you high?** Most fibre and grain hemp has too little THC to produce the effects reported for drug-type cannabis, because it is bred to stay under about 0.3% THC. Some 'hemp' flower is bred high in CBD and close to the legal THC limit, and THC-rich plants can appear in mixed seed. Effects are reported, not promised; legal status depends on testing, not on the name.

**Is CBD flower hemp?** CBD flower is usually legally hemp: drug-type-looking buds from CBD-dominant plants kept under the hemp THC limit, often 0.3%. Botanically it is the same species as THC-dominant cannabis, with a different synthase gene. CBD-dominant plants still make a little THC, so a crop can test over the limit, and rules on selling smokable hemp flower vary by place.

## Sources

1. Small E, Cronquist A. 1976. A practical and natural taxonomy for Cannabis. Taxon 25(4):405-435. https://doi.org/10.2307/1220524
2. Sawler J, Stout JM, Gardner KM, et al. 2015. The genetic structure of marijuana and hemp. PLoS ONE 10(8):e0133292. https://doi.org/10.1371/journal.pone.0133292
3. Small E. 2015. Evolution and classification of Cannabis sativa (marijuana, hemp) in relation to human utilization. Botanical Review 81:189-294. https://doi.org/10.1007/s12229-015-9157-3
4. Hillig KW, Mahlberg PG. 2004. A chemotaxonomic analysis of cannabinoid variation in Cannabis (Cannabaceae). American Journal of Botany 91(6):966-975. https://doi.org/10.3732/ajb.91.6.966