Cannabis Plant Anatomy: Flower, Leaves, Resin and Seeds

The plant in brief

NIDA describes cannabis as the dried leaves, flowers, stems and seeds of the Cannabis sativa L. plant. [1] This page walks through those parts as botany only. It gives no growing, harvesting or processing instructions. Chemistry is covered on Cannabinoids Explained and in Cannabis Chemistry.

NCCIH says the plant contains about 540 chemical substances. [2] One review puts the figure at more than 550 compounds. [3] Counts differ between sources, so treat both as rough.

Parts at a glance

Flowers

A review of cannabis glandular trichomes (tiny resin-producing structures) says cannabinoids are produced by stalked glandular trichomes located on female flowers. [4] These flower clusters are what many people mean by "buds." The glands themselves have their own page: Trichomes and Resin Glands.

Leaves and stems

NIDA lists leaves and stems among the plant parts that count as cannabis. [1] A review notes the plant has long been used as a source of textile fiber. [5] Proper evidence not found, in the sources read for this page, for a reliable plain-language comparison of cannabinoid levels in leaves versus flowers, so none is given here.

Resin

Resin is the sticky material made by the glands. The trichome review says the resin contains cannabinoid acids such as THCA and CBDA, along with many other plant chemicals. [4] How resin is separated into products such as hash is covered in the concentrates collection, starting with Hash and Kief. This page does not describe how to make any product.

Seeds

FDA states that the seeds of the plant do not naturally contain THC or CBD. [7] Hemp seed ingredients that FDA reviewed contain only trace amounts, which the seeds may pick up from other plant parts during harvesting and processing. [7] See Hemp Foods and Hemp Seed Oil for food questions.

Male, female and hermaphroditic plants

Botanists describe cannabis as dioecious, meaning plants are usually either male or female. In nature, male and female plants are found with nearly equal frequency. [8] Some plants carry both kinds of flowers and are called hermaphroditic. [8] This is a statement about plant biology, not a guide to sexing or tending plants.

Hemp and marijuana: same species, different definitions

NCCIH explains that "marijuana" refers to plant parts or products containing substantial THC, and that cannabis plants with very little THC are considered "industrial hemp" under US law. [2] For US federal purposes, FDA reports that hemp is defined as the plant and its derivatives with a delta-9 THC concentration of not more than 0.3 percent on a dry weight basis (read 2026-10-22; laws change and this is not legal advice). [7] See Hemp vs Marijuana for the full comparison.

What about "ruderalis"?

Historically the genus was described under three names: Cannabis sativa, Cannabis indica and Cannabis ruderalis. A 2023 genomics review says the latest evidence points toward one highly diverse species instead of several. [9] A neurology overview describes ruderalis as having very low THC and as flowering with age rather than with changes in day length; it is mainly used in hybrids for that trait. [10] Retail words such as indica and sativa are a separate topic: see Botanical Classification vs Retail Labels.

Safety note

Any cannabis plant material or product can harm a child or pet that swallows it. FDA advises keeping these products out of reach of children, and says a child who may have swallowed one should be taken to a physician or emergency department. [7] In the US, call 911 for an emergency or Poison Help at 1-800-222-1222. See Accidental Child and Pet Exposure and Poison Help by country.