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Weed Plant Anatomy 101

If you’re growing marijuana, it helps to understand the basics when it comes to weed plant anatomy. Here is a basic guide to give you the rundown:

  • Cola – Buds that grow at the end of each branch on your cannabis plant.
  • Bract – The leaves that develop a teardrop shape and are covered in resin glands.
  • Calyx – The marijuana bud itself.
  • Trichomes – Tiny, bulbous globes that are filled with cannabinoids, such as tetrahydrocannabinol (THC) or cannabidiol (CBD). They also contain aroma-producing terpenes.
  • Fan Leaves – The larger leaves found on the cannabis plant.
  • Nodes – The part of the plant that fan leaves grow out of.

As you can see, there are many characteristics of the marijuana plant. However, we’ve left out pistils and stigmas in order to dive deeper into them:

What are Pistils?

Simply put, pistils are a female cannabis sex organ. They produce tiny hair-like strands called stigmas and these collect pollen from male cannabis plants.

Upon pollination, pistils will begin to develop seeds. While this is a natural part of the cannabis plant cycle, as a grower, you’re looking to avoid this process. When female plants start to produce seeds, they take their focus away from developing resinous flower. In turn, this makes your marijuana less potent.

When cannabis begins to sprout, stigmas will initially appear as white strands. However, as the plant enters the flowering stage, these stigmas will become darker and produce a yellow and orange coloring.

Pistils in Young Cannabis Plants

Generally speaking, young male cannabis plants will preflower before females. In fact, this is a good indicator of the sex of your cannabis plant.

If you bought regular seeds (in substitute for feminized seeds), this is a good time to determine whether or not you have male or female plants. If you notice pistils appearing randomly throughout the plant, it’s likely a male. Under such circumstances, you’ll want to get rid of these plants as they will downgrade the potency of your female plants.

Preflowers can be indicated by the stipule, a green “hair-like” growth that appears at the stem. When white hairs emerge from nodes, this means you have a female plant. While growth cycles vary depending on the strain, some female plants can take up to 8 weeks to leave the vegetative stage.

For this reason, it’s in your best interest to purchase feminized seeds.

Pistils in Mature Cannabis Plants

As mentioned, if your plant matures into a male, you’ll want to remove it from your garden immediately. This will prevent female plant stigmas from encapsulating pollen in their pistils.

If your plants mature into females, you can use pistils and stigmas as a means of knowing when it’s time to harvest.

Within the first few weeks of the flowering stage (when the buds form), you should start to see white hairs coming out of the pistils. For about 4 to 5 weeks, these stigmas will remain white. However, they will eventually start to develop a yellow coloring.

The color of stigmas will vary depending on the strain. For example, some stigmas will remain yellow throughout harvest while others will develop red, amber, or dark brown coloring.

If you’re new to growing cannabis, it can be difficult to determine when exactly to harvest. We recommend waiting until 50% of your plant’s stigmas have developed some form of coloring. If you’re more experienced with growing, 70% to 80% is a more ideal solution. It’s during this period the buds are the most potent.

Pistils in Mature Cannabis Plants

Don't Let Stigmas Dry Out!

If you wait too long to harvest your cannabis plant, stigmas will develop a dark brown coloring and dry out. While the marijuana bud this produces will still get you high, much of the THC will degrade to cannabinol (CBN).

In turn, this will create poorer quality in taste and overall potency. On top of this, some people report high levels of CBN make them feel fatigued and sluggish.

That said, it’s vital to keep an eye on your pistils and stigmas. As a reminder, stigmas will have white hairs for about 4 to 5 weeks within the flowering stage. It isn’t until 7 to 10 weeks you’ll notice orange, red, and yellow hair coloring.

Keep in mind that, like females, hermaphroditic plants will also produce pistils and stigmas. Yet, “hermies” will also produce pollen and pose a threat to your cannabis plant.

What if Buds Keep Making New Pistils?

If you’re new to growing cannabis, it’s best to stick with one strain. This will ensure that the buds on all your plants will be ready to harvest around a similar timeframe.

Still, how varying strains grow buds can be confusing to new growers. Some strains will produce buds at the top of the plant while others at the bottom.

On top of this, you can still run into issues when growing the same strain. You may notice one plant maturing at a quicker rate than another. This isn’t too big of an issue – you can always harvest “parts,” beginning with your most mature plants.

However, if you have a plant that’s ready to harvest and continues to develop pistils, you may have an issue. And there are several reasons as to why this is occurring.

One of the most common is heat stress which results in new pistils developing close to your plant’s light source. If this is the problem, you may also notice buds growing in unusual shapes or new buds covered in sugar leaves.

It’s also common for some strains to simply grow new pistils during the flowering stage. This is most prominent in Sativa plants and Haze varieties. In such cases, you’ll likely notice a reasonable amount of white pistil growth developing evenly over buds. This is normal and a bit of a quirk to these strains.

Red Hairs on Marijuana Plants - Final Word

As discussed, the red hairs found on marijuana plants are known as stigmas and develop from pistils. While it’s not always the case, higher-quality cannabis generally has large amounts of these hairs.

Initially, these hairs will appear white. However, as the plant matures, these hairs will develop a red, yellow, or brown coloring.

Keep an eye on your stigmas and pistils are you get ready to harvest. A general rule of thumb is to harvest when 50% of your plant’s hairs have developed coloring.

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