A cannabis plant has roots, a main stem with nodes, fan leaves, and, on females, flowers made of bracts, stigmas and resin glands called trichomes. The trichomes are where cannabinoids and aroma compounds are made, which is why the female flower is the part people use. Understanding each part explains almost every growing and shopping decision, from why males are removed to why buds are inspected under magnification.
Cannabis is an annual, herbaceous plant, and most plants are either male or female (Betancourt et al., Plants, 2026; Babaei and Torkamaneh, Plant Genome, 2026). This guide goes from the ground up and focuses on the structures that matter for growers and consumers.
Weed Plant Anatomy at a Glance
| Part | What it does | Why it matters |
|---|---|---|
| Roots | Anchor the plant and take up water and nutrients | Healthy roots tolerate training better |
| Main stem and nodes | Carry water and sugars; nodes are where branches and leaves attach | Growers count nodes to time topping |
| Apical meristem (growing tip) | Drives upward growth; suppresses side branches | Topping it creates more main branches |
| Fan leaves | Capture light for photosynthesis | Few resin glands, so they are not the product |
| Bract and stigmas (female flower) | Bract encloses the ovary; two stigmas catch pollen | Stigma color is one harvest cue |
| Trichomes | Resin glands that store cannabinoids and aroma compounds | Color change signals maturity |
Roots, Stem and Nodes
The root system anchors the plant and takes up water and minerals. A 2025 review of training techniques points out why this matters: plants started from seed develop a decent root system and survive topping better, while the authors consider clonally propagated hemp, with its thinner root structure, poorly suited to hard training (Ijoma et al., J Cannabis Research, 2025).
The stem is built from repeating units. Each unit has a node, the point where a leaf attaches, an internode, the stretch of stem between nodes, and an axillary bud, a dormant bud in the angle between leaf and stem. The 2025 review describes this unit as a phytomer. The tip of the stem, the apical meristem, produces new units and releases hormones that keep the side buds quiet. This is called apical dominance, and it is why an untouched cannabis plant grows one tall main stem (Ijoma et al., 2025).
Fan Leaves
Fan leaves are the broad, fingered leaves that everyone associates with cannabis. They collect light for photosynthesis. Resin glands are found much less often on vegetative leaves and stems than on flowers: the most productive gland type sits mainly on the female bracts and on the small leaves of the inflorescence, with far fewer on vegetative leaves and stems (Betancourt et al., 2026). That is why growers and processors treat large fan leaves as plant waste to be removed rather than as product. For what that means at harvest, see our guide to trimming cannabis plants.
Male, Female and Hermaphrodite Plants
Cannabis is predominantly dioecious: females carry two X chromosomes and males an X and a Y. Monoecious plants, with both sexes, and hermaphrodites can occur (Babaei and Torkamaneh, 2026). In that study, researchers recorded the first flower to tell the sexes apart. Male flowers form as bell-shaped, closed sepals; a female flower has a symmetrical calyx with two styles.
Sex determines the plant’s role. Males produce pollen; pollination of females is known to reduce cannabinoid content, so growers separate male plants before flowering (Babaei and Torkamaneh, 2026). The National Cancer Institute adds that cannabinoid concentration is highest in the female flower (NCI PDQ, Cannabis and Cannabinoids).
The Female Flower: Bract, Stigmas and Calyx
A female cannabis flower is simple. Researchers describe a reduced outer layer, a bract that encloses the ovary, and two stigmas that catch pollen (Betancourt et al., 2026). The bract is where most resin glands form. In the finished plant, many of these flowers pack together on a branch tip to form the cluster called a cola, a term used for the cannabis inflorescence. In an untrained, healthy feminized plant, one dominant apical cola usually forms with smaller colas on side branches (Ijoma et al., 2025).
Stigmas change color as flowers ripen. The 2026 landrace study used the browning of stigmas, along with trichome color, to judge maturity (Babaei and Torkamaneh, 2026).
Trichomes: Where the Cannabinoids Are Made
Trichomes are the plant’s resin glands. The 2026 review distinguishes glandular trichomes, which store specialized compounds in a cavity near the tip, from non-glandular ones such as hair-like trichomes. Glandular trichomes come in three types (Betancourt et al., 2026):
- Bulbous: the smallest, about 10 to 20 micrometers across.
- Sessile: a larger round head on a very short stalk, more than 30 micrometers.
- Capitate-stalked: the largest type, with a visible stalk and a wide head. It is the type tied to peak cannabinoid accumulation.
Gland density rises from the first week of flowering, and glands reach maturity, marked by peak cannabinoid accumulation, around five weeks after they start to form (Betancourt et al., 2026). Growers read the color: a 2025 review says buds are typically ready when about 60 to 70% of trichomes have turned amber (Ijoma et al., 2025).
THC, CBD and aroma compounds called terpenes are the substances stored in these glands. What a particular strain delivers depends on its genetics; see our strain directory or the guide to sativa and indica to understand why the labels on jars say less than people think.
Putting Anatomy to Work
Each part suggests a practical rule. Protect the roots by not over-stressing young plants. Remove males before they shed pollen. Use training to expand the canopy so light reaches more flowers; see scrogging and trellising. Inspect trichomes before harvest. For the full growing sequence, read basic marijuana growing and the cannabis life cycle.
Growing at Home: Washington and Oregon Law
Home growing is legal for adults 21 and older in Oregon, up to 4 plants per household, kept out of public view; see the statute (ORS 475C.305) and our Oregon marijuana laws guide. In Washington, home growing is legal only for registered medical patients. Under RCW 69.51A.210, a patient entered in the state medical cannabis authorization database may grow up to six plants by default, or up to fifteen if a health care professional recommends it. Adults who buy only at retail stores may not grow. See our Washington marijuana laws guide. Cannabis remains illegal under federal law, and local rules and landlord or HOA restrictions can add limits.
Weed Plant Anatomy FAQ
What are the main parts of a cannabis plant?
Roots, stem with nodes, fan leaves, and flowers. Female flowers consist of bracts, stigmas and resin glands called trichomes.
Which part of the cannabis plant has the most THC?
The female flower. Cannabinoid concentration is highest there, and the resin glands on the bract store the compounds.
What are trichomes?
Tiny resin glands on the surface of the plant. Glandular trichomes store cannabinoids and other compounds, and they change color as the flower matures.
How can you tell a male cannabis plant from a female?
By the first flowers. Male flowers form as bell-shaped, closed sepals, while female flowers have a symmetrical calyx with two styles.
What is a cola?
A cluster of flowers at the top of a stem or branch. The main cola sits at the top of the plant, with smaller colas on side branches.
Do fan leaves contain THC?
Very little compared with flowers. Resin glands are concentrated on female bracts and inflorescence leaves, with far fewer on vegetative leaves.
For adults 21+ in legal states. General information, not medical advice.
