Anatomy of a cannabis seed

In a previous blog post we explained how to distinguish superior cannabis seeds from their poorer quality counterparts. Selecting quality, viable seeds is the first crucial step for a cultivator growing healthy plants that produce a high yield.

Very few of us however are aware of the anatomy of these seeds, or the role each component plays in the growth of the plant, yet cannabis seeds are fascinating organisms which deserve detailed attention.

Radicle

The radicle is the first growth that will emerge from the seed during the process of germination. Known as the ‘primary root’, or the ‘embryonic root’, it grows downwards into the soil in order to start absorbing the water, minerals and other nutrients the plant requires for growth.

If the radicle begins to decay, the seedling will die off before emerging above the soil. This is known as ‘dampening off’ and is visible on the radicle as dark spots.

Root Cap

The root cap is shaped like a thimble or dome, and sits on the end of the radicle. It’s comprised of multi-layered tissue similar to that of the shoot apex.

The root cap performs two primary functions: first, it is responsible for anchoring the plant by ensuring that the root continually grows downwards into the soil (if the root cap is removed without damaging the radicle, the root will grow in an irregular direction which may not be conducive to plant stability). Second, the root cap is responsible for protecting the tip of the radicle from damage as it pushes its way down through the soil.

Cotyledons

Known as the ‘embryonic leaf’ in seed-bearing plants, these are the first small leaves which start to emerge. Emergence from the seed takes place within twenty-four hours of the radicle entering the soil.

Cannabis seeds contain two cotyledons, placing them within the dicotyledon “dicot” category of flowering plants (plants whose seeds contain only one cotyledon are referred to as “monocots”). “Dicot” seedlings contain cotyledons which are photosynthetic, thereby driving the growth of the seedling as soon as they emerge from the soil.

These cotyledons are the first visible sign of growth (due to their being above ground) and they contain the stored nutrient reserves of the seed. Cotyledons are responsible for encouraging leaf growth during the early stages of the plant’s life. As such, the first true leaves will emerge from within the cotyledons. As these true leaves become established and the cotyledons are no longer required, they will turn yellow and die.

The cotyledons are vital for the plant to be able to breed.

Shoot Apex

As mentioned earlier, the shoot apex is made of similar material to the root cap. It is also a similar shape. However, in contrast to the root cap, the shoot apex is comparatively long.

The shoot apex is the growing tip of the plant, and is protected by young leaves.

Primary Leaves

As the name implies, these are the first true leaves to emerge after the cotyledons. They emerge from the top of the initial long, thin stem attached to the shoot apex. These leaves enable the plant to continuously seek the sunlight it requires to further develop.

Primary leaves emerge prior to cell division within the stem which then results in secondary growth.

Calyx

This is the first part of the flower to form. If looking at more orthodox, colourful flowers, the calyx is identifiable as the tight green bundle of growth (“sepals”) directly underneath the petals which hold the flower together.

The calyx contains the reproductive organs of the plant, called the “pistils” and the “trichomes”, and is designed to protect them. The pistils are where the long hairs (called “stigmas”) emerge from, while the trichomes are the resin glands.

Female calyx resemble small seeds. Once they are ready for pollination they will burst open to expose white pistils. Male plants form pollen sacs which usually drop low. Once mature, these sacs will burst open and release pollen into the air, thereby pollinating the females.

Perianth

The petals of a flower form the “corolla”. The corolla and the calyx combined comprise the perianth.

The perianth is the non-reproductive part of the structure, designed with the sole purpose of protecting the plant’s reproductive organs.

Closing Thoughts

If you enjoyed this article, take a look at our piece on the anatomy of the cannabis plant. Understanding anatomy of both seed and plant will help you nurture a seedling into an established plant that produces a good quality harvest, and make growing an increasingly rewarding process.

For those of you that are interested in buying cannabis seeds, view our selection for sale here and start your very own collection!