Have you ever been curious about the anatomy of a cannabis plant? What exactly is a bract or calyx? A pistil or stigma? And what’s the difference between a fan leaf and a sugar leaf? 

If you’ve come across this article, chances are you’re trying to understand these terms and how they impact your plant’s growth, potency, and yield. Discover the different parts of a weed plant and don’t stress if you mix things up—this industry has been using some of these terms incorrectly for years.

Cannabis Plant Anatomy 101

Bracts

Bracts are small, leaf-like structures that surround the calyx, though these terms are often used interchangeably and incorrectly.

These tiny structures make up most of the bud, protecting the flower’s reproductive organs and housing most of the plant’s resin glands. Bracts contain high concentrations of cannabinoids and terpenes, making them a key part of the flower’s potency. They also shield the calyx and reproductive organs from environmental stress and herbivores.

Calyx

The calyx is a crucial part of the flower, forming the base of the reproductive structure.

It is the first part of the flower to form, holding the pistils and stigmas, and it’s surrounded by bracts. The calyx is an integral part of the plant’s reproductive system, as it contains the pistils and stigma. In terms of growth, the calyx protects the seeds if fertilized, though most growers aim for seedless flowers.

Stigma and Pistil

These are key parts of the flower’s reproductive organs. The pistil includes the stigma, style, and ovary. In the cannabis world, the pistils are the hair-like structures that collect pollen, but if you asked a botanist what those are, they would call them the stigma. 

“Pistils” are an indicator of the plant’s maturity and health. Initially, they are bright white, and as your plant nears the end of its life cycle, they often turn brown, amber, or orange and shrivel.

Cola

A cannabis cola is a cluster of cola is a cluster of bracts and calyces that forms at the top of the plant or on smaller branches. The main cola, or apical bud, grows at the very top of the plant, while secondary colas develop along the sides. 

The size and density of colas often indicate the plant’s overall health and yield. Larger colas mean more buds to harvest. The plant’s energy focuses on developing colas, especially when growers use techniques like topping to encourage multiple main colas.

Fan Leaves

Fan leaves are the iconic, large cannabis leaves often associated with cannabis imagery.

These large, multi-fingered leaves are essential for photosynthesis. While they are not consumed, fan leaves play a vital role in the plant’s energy production. They capture sunlight and convert it into energy, fueling the plant’s development.

Sugar Leaves

Sugar leaves are smaller leaves that grow within the buds. These leaves are coated with trichomes, giving them a sugary appearance.

While not as potent as the flower, sugar leaves are often used to make edibles, concentrates, or pre-rolls. They support bud development and act as an additional site for photosynthesis.

Flower (Cannabis Bud)

The flower, often referred to as the cannabis bud, is the amalgamation of calcyces and bracts that make up a cola. The flower is the entire reproductive organ of the female cannabis plant and the part harvested for consumption. It contains high concentrations of cannabinoids and terpenes, the compounds responsible for the plant’s effects and aroma. Cultivators focus on maximizing flower production because it determines the plant’s yield and potency. 

For consumers, the flower is where the desired effects of cannabis come from. In nature, flowers attract pollinators and, if fertilized, produce seeds. In cultivation, unfertilized flowers (sinsemilla) are preferred as they concentrate more energy into producing resin instead of seeds.

Node

Nodes are the points on the stem where branches or leaves grow. These junctions are where important parts like fan leaves, sugar leaves, and colas develop. Knowing how to identify nodes helps growers determine where to prune or train their plants. Internode spacing, which is the distance between nodes, can reveal whether the plant is receiving adequate light. 

When light levels are optimal, plants develop tighter internode spacing, resulting in a more compact structure and more potential bud sites. Growers typically aim for tighter internode spacing to maximize yields and create healthier, more productive plants.

Roots

Roots are the foundation of the plant, hidden beneath the soil. The root system anchors the plant and absorbs water and nutrients. Healthy roots lead to robust growth and higher yields. 

Roots also host beneficial microbes that help protect the plant and break down nutrients. Mycorrhizal fungi are one type of microbe that has a symbiotic relationship with cannabis roots and can give the appearance of fuzzy white hairs covering the root.

Stem

The stem is the main support structure of the plant.

It’s the central stalk that carries nutrients and water throughout the plant. A strong stem ensures the plant can support heavy colas and resist environmental stress. It serves as the plant’s transport system, connecting roots to leaves and flowers.

Trichomes

These tiny, crystal-like structures are where the magic happens. Trichomes are resin glands that produce cannabinoids, terpenes, and other compounds. 

They are the source of the plant’s potency and aroma. Without trichomes, cannabis would lack its psychoactive and therapeutic effects. Trichomes act as a defense mechanism, deterring pests and protecting the plant from UV rays.

Key Differences Between Male and Female Cannabis Plants

Cannabis (Cannabis sativa) is a dioecious plant, meaning it produces distinct male and female plants rather than having both reproductive structures on the same plant. This separation of sexes is significant because only female cannabis plants produce the resinous flowers rich in cannabinoids like THC and CBD, making them the primary focus for cultivation. 

Male plants, on the other hand, play a crucial role in breeding by producing the pollen needed for fertilization, which leads to seed production. Understanding the difference between male and female plants is essential for growers who want to maximize flower yield while avoiding accidental pollination.

For centuries, cannabis cultivators in regions like India, Thailand, and Mexico understood that separating male and female cannabis plants resulted in more potent, seedless flowers. This practice became widely adopted in the 20th century, with American and Colombian growers refining sensimilla cultivation in the 1970s. While researchers like Jean-Baptiste Lamarck documented cannabis sex differentiation as early as 1785, it was traditional farmers and modern breeders who developed the techniques that revolutionized cannabis production, maximizing cannabinoid-rich flower yields.

To distinguish between female and male cannabis plant anatomy, growers must observe their pre-flowering characteristics, which become apparent a few weeks into the vegetative stage.

Male Plants

• Parts: Develop pollen sacs instead of bracts and calyces. 
• Importance: Males are essential for breeding but not for producing consumable cannabis buds.
• Role: Release pollen to fertilize female plants, leading to cannabis seed production.

Female Plants

• Parts: Produce calyces, bracts, and trichomes.
• Importance: Female cannabis plants are the source of cannabinoids and terpenes.
• Role: Focus energy on resin production, especially in unfertilized plants.

Cannabis Plant Anatomy Conclusion

Understanding cannabis plant anatomy helps growers make informed decisions about cultivation techniques like low-stress training, ensuring healthier plants and better yields. In fact, you can become a more successful cannabis cultivator once you can recognize the different parts of the cannabis plant and the unique roles they play.

All photos by Kandid Kush