Ultimate Guide to Cannabis Plant Anatomy
Many cannabis lovers are only familiar with two parts of the cannabis plant: the flower and the leaf. Many of them have never seen a fully matured cannabis plant up close.
When you grow marijuana, you should become familiar with cannabis plant anatomy. The function of each part of the plant and its relationship with the other parts of the plant is crucial to maintaining a healthy plant.
Male and Female Anatomy of the Cannabis Plant
Cannabis plants are dioecious in nature. That means their flowers have separate female and male parts. The male flower produces pollen sacs, while the female flower produces seeds. The female plants produce weed with high levels of cannabinoids, while the male plant has low levels. When the male and female flowers interact, the male fertilizes the female flowers, thus producing seeds that are used for cultivation and breeding. The female plant is known for producing weed rich in cannabinoids like THC.
The male plant has low levels of cannabinoids; however, it plays a crucial part in the fertilization and breeding process. Male plants are also a rich source of fiber.
This guide will focus on helping cannabis cultivators, as well as consumers, understand cannabis plant anatomy. Discussed below are the different parts of the marijuana plant, their functions and their relationship with the plant as a whole.
Determining Your Cannabis Plant’s Sex
Unpollinated female cannabis plants are the ones that produce large flowers. Once it’s pollinated, the plant will focus on creating seeds instead of growing the potent buds that we want. No one wants to smoke low-quality, seedy buds; that’s why you want to ensure that you keep pollen away from your female cannabis plants.
Usually, the first signs of your plant’s sex will show up about six weeks after it begins to grow. Watch the plant’s nodes (between the main stem and branches) for the first indications of your plant’s gender.
At those nodes, you’ll see one of two things start to form: pollen sacs or pistils (which look like hair). If you see pistils, there’s good news: it’s a female plant! If you notice pollen sacs, it means your plant is a male.
However, you might notice both pistils and pollen sacs, which indicates the plant is hermaphroditic (it’s both male and female).
If you want to produce the best, most potent buds, you’ll want to remove all of the hermaphroditic plants and males right away. Once they release pollen into the air, it latches onto the pistils of your female plants, making them produce seeds instead of big buds.
How to Spot High-Quality Cannabis Seeds
Speaking of cannabis seeds, let’s continue our anatomy exploration by looking at them more closely. Like any other flower, cannabis seeds contain the blueprint for its maturation. There’s a 50/50 chance of the seed growing into a male or female plant. Not too long ago, the only way to ensure you grow female plants that produce buds was to plant every seed and remove the males before pollination occurs. However, feminized seeds can take the guesswork out of growing female cannabis plants.
Those seeds contain the DNA of your future plant, meaning that healthy seeds grow healthy plants. Look for seeds that:
Related: Grow Weed Starting From Seed
Cannabis seeds have a hard outer shell to protect the embryo. The seeds develop into seedlings when exposed to the right environmental conditions, such as temperature and moisture.
The seedling or new plant grows its first pair of small rounded leaves referred to as cotyledons and root and shoot meristems. The green color of the cotyledons signifies the presence of chlorophyll, which allows the tiny leaves to conduct photosynthesis.
After several days, serrated leaves develop. This stage of growth is referred to as the early vegetative stage. This is the stage where the plant absorbs all the energy and nutrients and directs it to the upward nodal growth of the leaves and stems.
The cannabis plant has nodes that are parallel to the branches, but when the plant reaches the flowering stage, the spacing of the nodes becomes irregular. In this seedling stage, the cannabis plant anatomy consists of roots, stem, and leaves.
The tail that pops from the seed to the ground lengthens and thickens with the growth of the cannabis plant and eventually becomes the plant's taproot. From the taproot, lateral roots forming a fibrous network of roots in the soil appear. These roots are responsible for absorbing water and nutrients, which are essential for the growth of the plant. The marijuana plant has small and whitish roots that like to fill out their potting mediums. The sponge-like root network is responsible for keeping up with the high-water demand of the cannabis plant and is a vital part of cannabis plant anatomy.
As you germinate the cannabis seeds, you’ll notice the roots begin to appear. Early on, you’ll see the central taproot breakthrough, and once you transplant it into the soil, that taproot will continue to grow vertically, providing your stem with stability.
More delicate roots will grow and branch off from the taproot as the plant matures. Then, tiny hairs will emerge, helping your plant absorb and transport the nutrients it needs.
Because the roots will brand out widely, you’ll have to transplant the plant as it grows and matures. Without enough space, cannabis plants can become root-bound. Some warning signs to watch for are yellowing leaves, fast-drying soil, and unsteady plants.
After the cotyledons have broken out of the seedling to the surface, they are exposed to sunlight. This is important because cotyledons use photosynthesis to produce the energy required for the plant’s growth. After a few days, the cannabis plant develops its first pair of leaves that look like a marijuana plant (for example, serrated edges and a pointed tip). As the plant grows, more pairs of leaflets emerge and grow until the plant reaches its maximum, which may be five, nine, or more. This number depends on the strain of the plant.
The energy from the sun pooled with water and carbon dioxide is used by the leaves to make plant sugars. These sugars act as the plant's source of energy as they fuel growth and the biological processes of the marijuana plant. Marijuana plant leaves have low levels of THC. This contradicts the beliefs of some weed enthusiasts, who tend to believe that the leaves are the source of THC. The function of the leaves in terms of cannabis plant anatomy is absorbing sunlight. They also protect the delicate buds from sunburn by providing shade.
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These are the tiny leaves that appear on the cola. They look like they are coated in sugar, but those specks are actually trichomes. A marijuana plant’s genetics determine the density of the sugar leaves. Although they are weak sources of cannabinoids, marijuana consumers can smoke the leaves. They are also useful for edibles such as weed cookies.
Fan Leaves vs. Sugar Leaves
Fan leaves are an emblem of marijuana culture. You’ll find them on every branch, and the thin, pointy leaves help convert CO2 and light into energy. They also indicate the plant’s overall health. If these leaves begin to turn yellow or droop, it’s a sign that something’s off, whether it’s the nutrient levels, temperature, or water.
However, fan leaves aren’t too valuable in terms of effects. You can press minimal cannabinoids out of these leaves, but most people trim them off when harvesting their plants. This is because they don’t have the trichomes that secrete most THC and cannabinoids.
Sugar leaves are what we want. They are much smaller but play an essential role during photosynthesis. They have a dense coating of trichomes that resemble sugar and are rich in cannabinoids.
These characteristics are observed in the early flowering of the cannabis plant in the leaf-like structures that house pollen sacs. They appear as small pear-shaped structures that develop around branches that grow away from the stem. The presence of white, whip-like hairs on the bracts signifies that the plant is female, while the presence of full and bulbous (also referred to as crab claws) ones shows that the plant is male.
When growing cannabis plants for marijuana, the male plant should be ‘sexed’ before the emergence of the pollen sacs. This eliminates the tendency of pollen grains spreading to the female flower, causing it to produce seeds instead of resin. Weed from a fertilized plant does not provide an enjoyable smoking experience.
If you’d like to produce seeds, you should pollinate the flowers in a controlled environment. This helps to prevent cross-pollination.
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Branches and Stems
As a new pair of leaves grow from the previous set of leaves and push towards the sunlight, the main stem thickens and elongates. Located on either side of the stem are leaf nodes. Internode spacing is the distance between each pair of leaf nodes.
Mutations can result in irregular branching of the leaf nodes. Most growers remove the mutant cannabis plants immediately, even though they can still produce quality weed.
The central part of cannabis plant anatomy is the stem, as it provides support to the leaves, branches, and flowers. The stem houses a vascular system of tubes that supply water and other essential nutrients throughout the plant. Another part of the stem is the Xylem, which helps water and nutrients move seamlessly in the cells.
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Training the Cannabis Stem
A cannabis plant’s stem is like our spine. It’s a thick, vertical organ that supports new branches while providing stability as the plant grows upwards. The central stem also draws crucial nutrients and water, delivering them to the higher parts of the plant.
If it’s left to grow on its own, the plant’s stem will grow straight up in the air. While there’s not anything wrong with that, it doesn’t let you take advantage of the plant’s full potential. And if you’re growing with limited space, tall plants might not be the best bet.
However, there are ways to train your cannabis plant, which increases the yield and strengthens the central stem. The most common method involves bending the stem with twine, which increases light coverage. Usually called low-stress training (LST), it can significantly increase your harvesting yield with minimal effort.
Nodes partition the stem of a marijuana plant. They are found at the point where the plant branches off from the stem. In the early stages of marijuana plant growth, the nodes are parallel to each other, but as the plant begins flowering, the appearance of nodes along the stem length becomes irregular.
Nodes can help identify a cannabis plant’s species. In Indicas, nodes are close together, whereas in Sativas, the nodes are spaced out. These nodes are essential in the cannabis plant anatomy, as they are responsible for producing plant hormones. Nodes are also important for pinpointing a cannabis plant’s sex because here is where flowers will appear.
Flowers play several roles in plants, such as attracting pollinators and producing seeds once they are fertilized. As stated above, cannabis plants are dioecious in nature, and plants will have either male or female flowers.
The flowering process of the cannabis plant is vital in discerning whether the plant is a male or a female. The flowering top of a female plant is known as a cola. A plant typically has one main cola, but modern marijuana growers have come up with several methods of creating multiple main colas to help boost their yields. These methods include pinching, topping, or LST (low-stress training).
The topmost cola is known as the apical bud or main cola. It is the place where all the buds gather together to form a mass. Small clusters of colas grow between the fan leaves along the plant length. Compared to the main cola, the side colas are small, but they can be enlarged with both the LST and ScrOG (Screen of Green) methods. These two ways change the anatomy of the cannabis plant by exposing the buds to the sunlight, making them more prominent.
The flowers in male plants develop earlier than the female by a couple of weeks. They also do not have buds. It is always wise to wait for the pre-flower stage to distinguish between male and female cannabis plants. It is a male plant if a cluster of “grapes” starts to protrude, and there is no presence of white hair.
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Pistil and Stigma
This is the reproductive anatomy of the female flower. It has vibrant, hair-like strands known as stigma. The stigma’s function in the female flower is to collect pollen grain from the male flower and subsequently produce seeds.
During the maturity cycle of the marijuana plant, the stigma changes colors several times, from a white hue, yellow-orange, red, and lastly, a brown hue. In terms of potency or taste, they do not have any trichome, and will not provide the desired high effect.
Pistils are the best indicator of the plant's sex as they do not appear in the male flower. When they turn yellow, it is an indication that they are ready for harvesting. If you wait for them to turn brown, the flavor and potency of the weed are lost.
Calyxes & Bracts
These are the actual flowers of the marijuana plant. They are tear-shaped nodules found hiding between the tiny sugar leaves. Depending on the genetic strain, calyxes can appear in various colors, shapes, and sizes.
When the pistil is pollinated, the calyx is essentially turned into an ovary or seed incubator, which allows the seeds to grow. A non-pollinated calyx is rich in trichomes, which are responsible for secreting terpenes and cannabinoids, especially THC.
While many use the terms calyx and bract interchangeably, they aren’t the same. The tiny tear-shaped leaves are commonly called calyxes, but they are actually the perigonal bracts. These bracts are the most valuable parts of a cannabis plant; they produce dense layers of trichomes.
You can easily see the bracts on the lower part of your plant’s colas, but it’s impossible to see calyxes with the naked eye. The tiny calyxes are protective structures that cover female plants’ seed pods.
Near the bracts, you’ll find the hair-like pistils on your female plants that catch pollen from male cannabis plants.
Trichomes are the most minute part of cannabis plant anatomy but are also considered the queen of marijuana. They are small, hair-like formations, which are translucent and sticky to touch due to the resin coating the flowers. There are two types of trichomes: glandular and non-glandular. Non-glandular trichomes do not have a gland. Instead, they have small hairs that develop on the leaves, stems, petioles, and sometimes on the flowers.
Glandular trichomes are classified into three trichomes which vary according to their sizes with the most enormous (capitate-stalked trichomes) being produced on the calyxes and the surrounding sugar leaves. They can easily be seen as they consist of a stalk and a large gland head. Trichomes found in these calyxes and sugary leaves contain the highest number of cannabinoids and terpenes. As these trichomes develop, they tend to change color, from clear to an amber hue with a cloudy appearance. The second-largest trichome (capitate sessile) is made up of a head and a stalk. The third and smallest trichome (bulbous) appear on the surface of the entire plant. They are 0.00059 inches (10-15 micrometers) in length.
Trichomes are used to produce aromatic oils which are used for medicinal and therapeutic purposes.
The female marijuana plant is attractive to insects, animals, and other elements. The trichomes provide the plant with defense mechanisms. The sticky nature of the trichomes protects the plants from insects and pests. The crystal-like coating protects the plants against UV light. Their strong smell serves to keep away hungry animals. Trichomes also protect marijuana plants from wind and fungi.
Cola: The Star of the Show
After reading all of the above info about your cannabis plants, you’re probably wondering what part of the plant you actually use. Technically, you could consume the sugar leaves, but when people talk about smoking cannabis, they’re talking about the cola.
The cola is an aggregate of flower clusters that we call buds. They form an apex on the main stem and lateral branches during the flowering process. These buds contain the highest concentration of THC, terpenes, and cannabinoids.
The most prominent cannabis cola is found at the very top of the central stem; this is called the apical cola. If you let your plant grow naturally, the apical cola will dominate all of the other buds in terms of potency and size. However, by using training methods like the LST technique we mentioned earlier, you can increase the potency and size of multiple cola sites.
Harvesting Your Cannabis Plant
Apart from knowing about cannabis plant anatomy, it is also a good idea to know how and when to harvest the useful parts of the plant.
When marijuana plants exude a strong smell, they are ready for harvesting. Trichomes change color from white to amber, which signifies that they are ready to be harvested. For the best results, remove the fan leaves off the plant to expose the buds and speed up the drying process. To dry and cure your weed, hang the whole plant upside down for four days in a cool and dry place. You are then left with a beautiful bud, with its smell intact.
It’s always a good idea to avoid low-quality weed. You can recognize it by pricing, color, and bud density. Good quality weed is hard to squeeze and is crunchy and sticky to the touch. If the buds are leafy and easy to squeeze, then it is not the best quality.
Understanding cannabis plant anatomy is helpful for anyone that appreciates marijuana. Once you recognize the function of each part of the plant, you can develop a deeper appreciation for its beauty, function, and potency.
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