What Is Cannabis? Plant Biology and Common Terms
A plain guide to the cannabis plant: how it grows, what it contains, and what words like marijuana, hemp, THC, CBD and terpenes mean, with safety and legal pointers.
Content last updated . This page has not been medically reviewed.
In short
Cannabis is the name for the dried leaves, flowers, stems and seeds of the Cannabis sativa L. plant. [1] It is one plant used in very different ways: for fiber and seed oil, for products that make people feel "high," and as the source of a few prescription medicines. This page explains the plant and the words around it. It is education only, not medical or legal advice.Plant biology
- Origins. Cannabis sativa L. is a fast-growing plant that is thought to come from Central Asia. It has been used in folk medicine and as a source of textile fiber for a very long time. [2]
- Where the active compounds are made. Cannabinoids and terpenes are made and stored in tiny glandular hairs, called trichomes, on the plant's female flowers. [3]
- How many compounds. Sources give different counts. NIDA says at least 125 cannabinoids, NCCIH says about 540 chemical substances in all, and the FDA says more than eighty biologically active compounds. [1][4][5] We have not tried to reconcile these numbers.
- One species or several? Scientists still debate how to classify the genus. A 2015 genetic study said the genus has an inconclusive taxonomic organization, and that "sativa" and "indica" are two gene pools widely used to describe cultivated plants. It also found that marijuana-type and hemp-type plants differ across the genome, not only in THC genes. [6] See cultivars, chemotypes and strain names for what those labels do and do not tell you.
Common terms
| Term | Plain meaning |
|---|---|
| Cannabis | All products from the Cannabis sativa plant. [4] |
| Marijuana | Parts or products of the plant that contain substantial amounts of THC. Under US federal law, "marihuana" is listed in Schedule I of the Controlled Substances Act. [4][7] |
| Hemp | In US federal law, cannabis and its derivatives with no more than 0.3 percent delta-9 THC on a dry weight basis. [7] Hemp is mainly used for textile fiber and edible seed oils. [1] |
| Cannabinoid | One of a group of substances found in the plant. The two main ones are THC and CBD. [4] |
| THC | The cannabinoid mainly responsible for intoxicating effects: changes in mood, thoughts and perception. [1] |
| CBD | A cannabinoid that is not intoxicating like THC. [1] |
| Terpenes | Aromatic compounds in the plant; more than 100 have been identified. [8] |
| Concentrates, edibles, tinctures | Products made from the plant: extracted oils, foods and drinks, and cannabis-infused alcohol or oils. [1] |
Different forms, different timing
NIDA notes that people smoke or vape dried plant material, and that products now include oils and concentrates, edibles, tinctures and skin products. Edibles typically take longer to show effects, which can lead people to use more and raises the chance of serious negative effects. [1]Strength has changed
NIDA reports that the delta-9 THC potency of illegal cannabis seized by law enforcement rose from 3.96 percent in 1995 to 16.14 percent in 2022, and that flower and concentrates in dispensaries can exceed 40 percent. [1] Older descriptions of "what cannabis does" may not match today's products.What regulators say about it as a medicine
The FDA has not approved the cannabis plant for any medical use. It has approved several drugs that contain single cannabinoids. [4] Evidence label: approved medicine applies only to those specific drugs, covered in approved cannabinoid medicines. For the plant itself, evidence varies by condition; see clinical research overview.Safety and legal pointers
- Children. Accidental eating of cannabis edibles by children is a growing concern and can lead to hospitalization. [1] If you reasonably suspect a child swallowed a cannabis product, the FDA says to take the child to a physician or emergency department, especially if the child acts unusually or feels sick. [7] In the US you can also call Poison Help at 1-800-222-1222; see Poison Help by country.
- Medicines. Cannabis may interact with other medicines. [1] See how interactions work.
- Laws. US federal law and state laws differ, and laws change. This page is not legal advice. See cannabis and CBD laws.
Frequently asked questions
Is cannabis the same as marijuana?
Not exactly. NCCIH says "cannabis" refers to all products from the plant, while "marijuana" refers to parts or products with substantial amounts of THC. [4]
Is hemp cannabis?
Yes, hemp is cannabis with very low THC. In US federal law it means no more than 0.3 percent delta-9 THC on a dry weight basis. [7] Hemp-type and marijuana-type plants also differ genetically. [6]
Are indica and sativa different species?
Scientists still debate classification, and a genetic study found that marijuana strain names often do not reflect a meaningful genetic identity. [6]
Is cannabis approved as a medicine?
The FDA has not approved the plant for any medical use, but it has approved drugs containing individual cannabinoids. [4]
Is cannabis legal?
It depends on the country and, in the US, on the state. Under federal law, marijuana remains in Schedule I and hemp is defined by the 0.3 percent THC limit. [7] Laws change; check current local rules.
References
- National Institute on Drug Abuse (NIDA). Cannabis (Marijuana) DrugFacts. Read 2026-10-22.
- Andre et al. Cannabis sativa: The Plant of the Thousand and One Molecules. Frontiers in plant science. 2016. PubMed abstract read 2026-10-22.
- Nolan et al. Bigger is better: modern Cannabis trichomes are larger and more productive than their landrace ancestors. Plant & cell physiology. 2025. PubMed abstract read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH). Cannabis (Marijuana) and Cannabinoids: What You Need To Know. Read 2026-10-22.
- US Food and Drug Administration. What You Need to Know (And What We're Working to Find Out) About Products Containing Cannabis or Cannabis-derived Compounds, Including CBD. FDA page states content current as of 03/05/2020. Read 2026-10-22.
- Sawler et al. The Genetic Structure of Marijuana and Hemp. PloS one. 2015. PubMed abstract read 2026-10-22.
- US Food and Drug Administration. FDA Regulation of Cannabis and Cannabis-Derived Products, Including Cannabidiol (CBD): Questions and Answers. Read 2026-10-22.
- Rock et al. Constituents of Cannabis Sativa. Advances in experimental medicine and biology. 2021. PubMed abstract read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.