Anatomy of the Cannabis Plant: From Roots to Pistils

Although most cannabis plants are grown for their buds or flowers, there are more parts that make the cannabis plant what it is. What are the different parts of the cannabis plant and their functions, and what makes the anatomy of the cannabis plant?

In nature, cannabis plants are annual flowering plants. This means that they complete their life cycle, from germination to seed production, in one year.

Indoors, however, cannabis plants can survive longer than a year when grown under controlled conditions. If you keep them healthy and in constant vegetation, they can easily live for several years. “Mother plants“, from which you take cuttings or clones, often live longer than a year.

Cannabis is usually a dioecious plant, which means that the plants can be either female or male. However, sometimes monoecious plants occur, often called hermaphrodites, because they have male and female parts. With modern genetics, and increasingly found with feminized seeds, this is due to induced stress or unstable genetics.

Most people who are not cannabis growers are only familiar with two parts of the cannabis plant – the buds (or flowers) and the iconic leaves. But cannabis, like all other plants, consisists of many more botanical elements.

Here, from bottom to top, are the basic parts of the cannabis plant and their functions:

Seeds

Cannabis seeds are both the beginning and the end of the cannabis plant’s life cycle. Naturally, cannabis plants start from seed and end their life cycle when the plant has produced fully mature seeds. Cannabis plants grown from seed grow faster, are stronger, produce a higher yield, and have better quality than plants grown from clones or tissue culture.

Cannabis seeds form in female flowers. After pollination and successful fertilisation, the plant forms a zygote, which is a single cell. Through division and cellular reproduction, it eventually forms a multicellular embryo. After pollination, it takes about 30-45 days for the seeds to fully mature.

The embryo consists of an embryonic root, also called a radicle, an embryonic shoot and two cotyledons. The embryonic root first forms the main root, called the taproot, from which the root ball branches and forms.

The embryonic shoot also called the shoot tip, forms the stem of the cannabis plant. And the small cotyledons are the ones that photosynthesise and provide the nutrients for the seedling to grow.

Regular and feminized seeds

Naturally, the male plant will pollinate the female, and the female will produce seeds. These seeds produce either male or female plants, roughly 50/50 %, and they are called regular seeds.

But cannabis seeds can also be feminized, producing only female plants. To make feminized seeds, growers and cultivators do not even need the male plant. By triggering stress, usually by interrupting the light cycle during flowering or applying solutions such as colloidal silver or silver thiosulphate, they can trigger the production of pollen sacs on female plants.

Since these pollen sacs are developed on female plants, they carry only female genes. If this pollen is transferred to another female plant, the resulting seeds will almost always produce female plants.

Most common use of feminized seeds is with autoflowering strains. If you’re curious to learn more, you can do so here.

Roots

Although the above-ground parts get most of the attention and admiration, the roots are the most important part of the cannabis plant. Not only do they provide anchorage and stability for the plant, but they also provide nourishment for the entire plant.

Starting from the embryonic root, the root system begins to develop. Once the main root cord or taproot has grown, the later roots branch out and form a root system, sometimes called a root ball.

The two most essential functions of the roots are to supply the plant with water, nutrients, and oxygen and to transport the sugar stored in the leaves into the rhizosphere. Once the sugar has been transported into the soil, bacteria and other beneficial organisms such as fungi and worms will convert this sugar into usable food for the plant.

The same happens with nutrients that are trapped with organic material. They first must be broken down so that the roots can absorb them and transport them upwards into the plant.

The upper part of the root system is sometimes called the root crown. The root crown is the part of the root system where the tissue begins to change from root to stem. These roots are tougher, larger, and stronger due to the changes in the vascular system and contact with air and oxygen.

Stem

The stem or main stalk connects the roots and other parts of the plant. The main components of the stem are inside it and form the vascular system, which consists of the xylem and phloem.

The xylem is responsible for transporting water, minerals, and nutrients from the roots to the leaves, branches, and buds.

The phloem transports sugars, proteins and other organic compounds produced during photosynthesis to the roots and other parts of the plant.

The function of the stem is to give the plant structure and stability. As it grows, it becomes thicker and more elongated.

Nodes and internodes

Nodes are where the branches or stalks of the leaves extend from the stem and other branches. Internodes or internode distances are simply the distances between the individual nodes.

The spacing between nodes is primarily genetic. Indica-dominant plants tend to have narrower nodes, while sativa-dominant plants tend to have larger internodes.

Internodes can also be manipulated by lowering or raising the lighting indoors. The closer the light source is to a plant, the narrower the internodes.

Stipule

Stipules appear at the nodes, usually in pairs, but they can also grow singly. They look like tiny, thin leaves or daggers and can often be mistaken for pistils and signs of pre-blooming.

The exact role of stipules in cannabis is unknown, although some botanists believe their role is to protect young, newly formed leaves. In other plants, the stipules typically grow into thorns.

Branches

Together with the stem, the branches form the structure of the whole plant. They are covered with leaves and later with flowers and form a dense canopy. Depending on genetics and training, the cannabis plant has more or less later branching. That is why some plants are wider and bushier, and others are shaped more like a Christmas tree.

Stems and branches consist mainly of plant cellulose and calcium. The branches also contain xylem, which transports food and nutrients from the roots via the main stem to the leaves and flowers.

Leaves

The iconic serrated leaves of cannabis are the best-known parts of the cannabis plant. Their main function is to photosynthesise and store sugar or food for the plant. Think of them as organic solar panels that supply the entire plant with energy.

The leaves of the cannabis plant are palmate or digitate, which means they are divided into finger-like lobes that extend from the base of the leaf. The edges are often serrated, and the leaves typically grow in alternating opposite pairs.

The shape of the leaves can vary, either due to genetics, as in the cultivars like Freakshow or Duckfoot, or due to mutations, such as variegation.

Sativa/Indica difference

Although the sativa/indica classification is becoming increasingly outdated, especially when it comes to the effects of cannabis, it is still reasonably valid in terms of morphology.

Sativa leaves are thinner, lighter, and tend to consist of more leaves or fingers, while indica leaves are thicker, darker, fatter, and typically have fewer blades. This is simply a genetic expression of the conditions in which they were created. Sativa genetics originate closer to the equator, in regions with higher temperatures, higher humidity, and plenty of sunlight.

Indica genetics originate from more severe, mountainous areas with stronger winds and harsher climates. To compensate for less sunlight, the leaves evolved into thicker, fatter leaves with much more surface area.

Although all cannabis leaves perform the same function, there are still some subtle differences in their appearance:

Cotyledon leaves

The cotyledons are the first parts of the cannabis plant to appear above ground. As they already contain chlorophyll, they synthesise CO2, water and sunlight into sugars and nutrients that the young seedling needs to grow.

The cotyledons usually come in pairs, but it is not uncommon for an extra third leaf. Unlike all the other leaves, they are not serrated. After they have grown a little, a pair of true leaves appear in the middle.

As soon as the plant has used up all the stored nutrients in the cotyledons, they change colour and fall off.

Fan leaves

Although the first pair of true leaves has only one lobe or blade, they have characteristic serrated margins and a pointed tip. With each new node that grows, the number of leaflets or leaf blades increases until they reach their maximum.

Fan leaves are typically the largest part of the cannabis plant. They do not contain many cannabinoids or terpenes and are not covered with trichomes like sugar leaves. But fan leaves are an essential part of any cannabis plant.

Their main function is to store water, capture sunlight and produce food through photosynthesis. They are also a good indicator of the plant’s health. Any nutrient deficiencies, drought or overwatering, pest infestation or signs of disease or stress will show up first on the leaves.

Signs of discolouration, wilting or mechanical damage to the leaves indicate something is wrong with the plant. Keep a close eye on the leaves to ensure your plant’s health.

The stomata are located on the underside of the leaves. Their job is to ensure the exchange of water vapour, oxygen, and carbon dioxide between the environment and the plant.

Sugar leaves

Sugar leaves is a name for the leaves that grow from the cannabis flowers. They get their name from the trichome glands, which are more prominent on them than on other leaves. They also have a higher concentration of cannabinoids and terpenes.

Although they still perform the same function as other leaves, their appearance is slightly different. They are thinner, have fewer blades, and are shaped more like a spear.

Pre-sexual structures

Cannabis is a dioecious species, which means that there are male and female plants. With modern genetics, mostly due to stress or unstable genetics, cannabis plants can also be hermaphrodites. This means that they form female and male reproductive organs on the same plant.

As the cannabis plant matures and approaches flowering, the pre-sexual structures or “pre-flowers” appear. Pre-flowers are just the beginning of the female or male sex organs. Both the female and male structures appear at the nodes or where the branches meet the main stem.

Female plants have small pear-shaped structures with white hairs growing from the bracts. Male plants have fuller, convex structures from which no hairs grow.

Stamens – the male reproductive organs

Male cannabis plants do not have flowers. Instead, they have pollen sacs shaped like small balls or eggs, usually about 5 millimetres in size, containing pollen grains. The stamen consists of the pollen sacs or “anthers” and the filament that holds the anthers to the plant.

As the male plant matures, the anthers open and release the pollen into the air and environment. When the pollen lands on the pistils of a female plant, the female plant begins to produce seeds and reproduce.

Flowers

Flowers or “buds” are the parts of the plant that contain the most cannabinoids and are the reason most people grow cannabis plants. Their main function is to collect pollen and produce seeds. Average growers want to keep this from happening. Pollination would shift the plants energy into producing seeds and ruin the quality of the flowers.

Although buds appear as compact structures, they are made up of clusters of many smaller parts:

Bracts

Bracts are small, teardrop-shaped structures that are modified leaves that, together with the bracteoles, enclose and protect the seed pod. They are located at the base of the flower and appear just before flowering.

Their size, shape and colour can vary from cultivar to cultivar. However, they are usually between 2 and 6 millimetres wide, and their colour can vary from green to purple, magenta, red, or blue.

Once the female plant has been pollinated, the bracts turn into a primitive ovary or seed incubator. They protect the seeds as they grow and mature and eventually detach.

The bracts have the highest density of resin glands of any part of the cannabis flower. They account for most of the weight and cannabinoids and terpenes in cannabis buds.

Calyx

Many growers and authors call the bracts calyxes, but this is incorrect. Female cannabis flowers have calyx cells, but they do not have a defined calyx. Calyx cells are part of the perianth, a transparent layer of delicate tissue that partially covers the ovule.

Pistils and stigmas

Pistils and stigmas are the female reproductive organs of the cannabis plant. The pistils are oval structures with a single ovule enclosed by bracteoles and bracts, and two hair-like structures growing at the tip called stigmas.

The stigmas are that which serves to catch pollen. In the beginning, they are straight and white. As the plant and its flowers mature, the stigmas begin to curve and change colour. The colour usually goes from white to yellow and then to brown.

Many growers refer to the stigmas – also incorrectly – as the pistil. However, the pistil is the entire reproductive organ, including the two stigmas.

Cola

Cola is the main bud of the plant, the top flower on the main stalk. Just as the flower comprises many smaller parts, the cola is a cluster of several flower formations amassed together. The cola is the largest and heaviest flower of the plant.

“Popcorn” buds

Popcorn buds is the name given to smaller flowers usually found in the lower part of the plant or at the bottom of the branch. As these plant parts do not get as much light as the upper parts, they tend to produce less resin and are less potent.

Trichomes

Trichomes are small mushroom-shaped resin glands that look like tiny crystals and cover the buds and sugar leaves. Although most trichomes are found on the buds, the stems, branches and leaves also have trichomes.

Both male and female cannabis plants have trichomes. They produce all the phytochemicals in cannabis, such as cannabinoids, terpenes, and flavonoids.

Trichomes can vary in shape and size, and there are different types of trichomes:

  • Capitate-stalked trichomes 100 µm         
  • Cystolithic trichomes 50 µm
  • Capitate sessile trichomes 20 µm
  • Bulbous trichomes 10 µm

All parts of the cannabis plant have their function and use. Starting from germination, through vegetation, and flowering, they all do their part in ultimately producing the best harvest. We hope you now have a better understanding of cannabis plant anatomy, all the different parts as well as their functions.

  • Disclaimer:
    Laws and regulations regarding cannabis cultivation differ from country to country. Sensi Seeds therefore strongly advises you to check your local laws and regulations. Do not act in conflict with the law.

Comments

2 thoughts on “Anatomy of the Cannabis Plant: From Roots to Pistils”

  1. Great info dont suppose you ve got any spare seeds goin for the outdoor climate in the uk this coming summer pls guys.tia ?

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    Sensi Seeds

    The Sensi Seeds Editorial team has been built throughout our more than 30 years of existence. Our writers and editors include botanists, medical and legal experts as well as renown activists the world over including Lester Grinspoon, Micha Knodt, Robert Connell Clarke, Maurice Veldman, Sebastian Maríncolo, James Burton and Seshata.
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