Cannabis Plant Anatomy: Tips for Successful Cultivation

While it is common to hear that cannabis “grows like a weed,” there is much more to cultivating quality cannabis than just planting it and letting nature do the rest. Understanding the anatomy of the cannabis plant is essential for growing a successful yield. From nutrients to pest control and everything in between, there is a lot to learn about growing cannabis. When growing from seed vs. a clone, it’s also crucial to be aware of how to tell a male cannabis plant from a female.

1. Cannabis Plant Anatomy: The Ins and Outs
2. Understanding the Sex in Cannabis Plant Anatomy
3. Flowering Signs to Look For in Cannabis Plant Anatomy
4. Determining the Gender of Your Cannabis Seeds

Cannabis Plant Anatomy: The Ins and Outs

The cannabis plant anatomy comprises many parts that allow the plant to grow to perfection as nature intended. Many of these parts are similar to that of other plant species, while others are cannabis-specific.

Seeds

Cannabis seeds, which can be purchased from various online retailers and physical stores, are the source of the cannabis plant anatomy. Seeds are necessary in order to continue the various genetic lineages of cannabis chemovars available today. In a cannabis plant, seeds can be located within calyxes and male buds. Seeds that germinate sprout and will grow a taproot, which will become the main root that anchors the plant.

Cotyledon Leaves

Cotyledon leaves are the very first leaves formed after seed germination. They can be found at the top of the newly germinated cannabis plant’s stem. Many, however, do not consider these leaves to be true leaves. Instead, they refer to them as “seed leaves,” as they are part of the seed anatomy rather than a leaf produced by the plant post-germination.

Stems

The stem of a cannabis plant is at the center of the plant’s anatomy. Sometimes known as the stalk, its central location provides support for branches, leaves, and cannabis buds. The stem consists of a vascular system that brings water and nutrients from the roots and growth medium to other parts of the plant.

Branches

Branches are located from top to bottom of cannabis plants and exist in locations where nodes form on the main stem. New stem structures “branch” out from the main stalk/stem of the plant. In addition to the stem, branches support leaves and flowers.

Nodes

Nodes form at the point where leaves grow from the main stem and branch out. They partition the stem into various branches. They are parallel in the beginning cultivation stages and become more irregular throughout the plant’s growth cycle. The node is also the location where marijuana plants show their pre-flower gender signs, which are responsible for producing plant hormones.

Roots

The roots of cannabis plants, like other plants, are vital to cannabis plant anatomy. They absorb water, nutrients, and oxygen from within the growing medium being utilized (soil, coco coir, clay pebbles, etc.). The root system is always located at the bottom of the cannabis plant’s stem.

Fan Leaves vs. Sugar Leaves

Fan leaves are the large, fingered leaves that form on cannabis branches and have become a major symbol in cannabis culture. While they are not a source of trichomes, terpenes, or cannabinoids, they still serve a crucial purpose in the plant’s anatomy. They are essential for photosynthesis and consist of the dorsal surface, apex, ventral surface, and petiole, all of which work together to help the plant to grow to fruition.

Sugar leaves are small leaves that grow from cannabis buds/flowers. These leaves are much smaller than fan leaves. They are typically covered in a layer of trichomes and packed with cannabinoid content near the end of the flowering stage of cultivation. Sugar leaves are often used by patients and consumers to make cannabis-infused edibles at home and can be found in “shake/trim” ounces found in dispensaries across the country.

Flowers or Buds

Cannabis buds are essentially the flowers produced by the cannabis plant. For this reason, you may hear the words “flower” and “bud” used interchangeably. Cannabis flowers form up and down the stem and branches of a female cannabis plant. These are the most sought-after part of the plant because they contain the most terpene and cannabinoid concentration (including CBD and THC). Note that before being utilized, the flower must be properly dried and cured.

Colas

Colas are found towards the top of a female plant’s main stem and largest branches. The cola consists of tightly woven buds that form a central cluster of cannabis flowers, some upwards of two feet in length. The main cola—sometimes called the apical bud—forms at the top of the plant, while smaller colas grow along the budding sites of lower branches. Colas develop in areas that receive the most light exposure, and they contain the highest concentration of cannabinoids and plant resins.

Bract and Calyx

Each female flower is produced from a single ovule, and bracts are small leaves that surround and protect the ovule. Bracts are covered in a high concentration of resin glands known as trichomes (which we go over below).

At the base of cannabis flowers, you will find a translucent layer that protects the ovule. That is the calyx of a cannabis plant. It is also where pistils grow to catch pollen. Bracts are sometimes incorrectly identified as a calyx.

Stigma and Pistil

A stigma is a sticky, hair-like structure that grows at the top of the pistils of the cannabis flower. It is also where pollen is collected from male marijuana plants. Stigmas are known to change color as the cannabis plant matures. They often start as white hairs before going through a spectrum of yellow to red and eventually turning brown around harvest. The pistils provide protection for the female reproductive organs of the plant (including the ovules and potential seeds).

Trichomes

Not to be confused with stigmas or pistils, trichomes are microscopic mushroom-shaped hairs that form the frosty layer of crystals on cannabis flower. They mainly grow on the buds/flowers, sugar leaves, and bracts of marijuana plants. Each trichome is made up of a stalk and head. Within the head of the trichome, the production of cannabinoids and terpenes takes place. Trichomes are responsible for the sticky resin that binds to your finger when you handle cannabis. They also serve as a defense mechanism against environmental threats and wild animals. When dried post-harvest and removed from cannabis flowers, they are known as kief.

Understanding the Sex in Cannabis Plant Anatomy

When it comes to understanding cannabis plant anatomy, determining your plants’ gender is essential to proper cultivation. It will take roughly four to six weeks for signs of gender to appear on a cannabis plant, as this is when pre-flowers typically begin to develop. Depending on the strain, environment, and grower, it is possible to see definitive signs of male or female gender before four weeks; however, it can sometimes take even longer for clear signs of gender to show. You should start to look for signs of gender as soon as the seedling begins to grow because it is essential to promptly separate males from females. There are actually three variations of gender when it comes to cannabis plants: male, female, and hermaphrodite (commonly known as “hermied”).

Female Cannabis Plants

The buds (or flower as it is often called) found in dispensaries come from female cannabis plants. Female cannabis plants produce cannabinoid-rich buds and have a much higher THC concentration than male plants. Females often offer a rich terpene profile along with a plethora of other cannabinoids and phytonutrients. The buds from female cannabis plants that have not been pollinated by male plants are seedless or have minimal seeds. This allows the plant to produce bigger, fatter, and more potent buds, and is why it is so important to separate males from females when cultivating flowers for medicinal purposes. This form of cannabis is commonly called “sinsemilla,” which translates to “seedless” in Spanish. Female cannabis plants are the desired gender for commercial and home growers alike.

Male Cannabis Plants

Male plants are not as sought after when it comes to utilizing cannabis for medicinal or recreational purposes because they don’t produce buds. However, breeders and manufacturers of cannabis-derived products rely upon male cannabis plants for pollinating female plants when crossing genetics to create new strains (such as indica vs sativa). The fiber of male plants is also utilized to make clothing, bed linens, towels, and other products. Additionally, the seeds from male plants can be used to create various oils.

Because male cannabis plants are responsible for pollinating females, it is essential to identify and isolate male plants from females, so they do not “hermie,” switch gender, or begin to produce seeds because of spontaneous and unwanted pollination.

Hermaphrodite Plants

When a cannabis plant switches gender and “hermies” due to pollination, whether intentional or not, it will have both female and male sex organs. Pollination isn’t the only cause of a hermaphrodite plant. Aspects such as light and water stress as well as nutrient deficiencies can all cause a plant to “hermie.” If you are not looking to create seeds or new strains of cannabis, it is essential that you also isolate any hermaphrodite plants from your female plants. Some also choose to remove the male organs from these plants, often utilizing tweezers, in hopes of still producing sinsemilla.

Now that you have a better understanding of why knowing the sex of your cannabis plant is essential, let’s explore some of the common gender signs that develop before the plant begins flowering that you should be on the lookout for. These are the signs that will ultimately tell you the gender of your plants.

Flowering Signs to Look For in Cannabis Plant Anatomy 

The cannabis plant anatomy of male and female plants each have distinct “pre-flower” characteristics. Pre-flower stands for the period of cultivation in which the plants have not yet begun to produce flowers/buds. During this stage, it is essential to pay very close attention to the nodes of your cannabis plants to determine gender. Male cannabis plants have nodes that appear around three to four weeks post-germination, while female cannabis plants tend to start showing pre-flower signs around the four- to six-week range post-germination (a little later than male plants).

More cannabis gender signs that you should start to see pre-flower are detailed below.

Male Cannabis Plant Anatomy to Look for Pre-Flower

Male plants begin to show their gender earlier than females on most occasions. Male pre-flowers are known to appear around three to four weeks post-germination. At this time, the plant typically has at least five internodes. The male organ and pre-flowers are pollen sacs that show up as tiny balls on the nodes of the plant. Sometimes, they have a banana-like shape that is often present when the plant is a hermaphrodite rather than a genuine male. These ball-like organs on male cannabis plants produce pollen and later grow together into clusters of male flowers or male buds. However, these male buds are small and are not as desirable as their female counterparts.

Female Cannabis Plant Anatomy to Look for Pre-Flower

Female cannabis plants tend to start showing pre-flower signs around the four to six-week range post-germination (a little later than male plants). Female pre-flowers look like a V-shaped pair of white hairs that form out of the calyx to make up the pistil, which will later form clusters to create female flowers or female buds. These are the pre-flower signs that most growers desire. For this reason, they often choose to germinate feminized seeds, which you can learn more about below.

Determining the Gender of Your Cannabis Seeds

Unfortunately, there is no definitive way to tell whether a cannabis seed will produce a male, female, or hermaphrodite plant. On the market today, you can find what are known as feminized seeds from reputable stores or growers. Breeders have bred these seeds to eliminate the male chromosomes; in return, they produce primarily female plants.

Sometimes known as female seeds, this form of cannabis seed is highly sought after by cultivators looking to grow cannabis buds to smoke or for extraction purposes. This is especially true in commercial grows as one single male plant could pollinate a massive crop of females and cause an enormous loss for the company. Keep in mind that even with feminized seeds, there is a very slight chance that a male plant will germinate from those seeds. Whether using regular seeds or feminized seeds, this is another reason why it is essential to consistently look for signs of gender changes even into the late flowering stage of cultivation.