psychedelicious
Bluelighter
A quick summary: Trichromes, biosynthesis of THC, & Indica vs Sativa
There seems to be an ungodly amount of confusion over THC, its physical location in the cannabis plant, and the purpose of it / trichromes. I hope this post will help out those not in the know to figure out what's going on with THC and trichs.
Trichromes and Cannabinoid Production
Trichromes are glandular hairs which are found on many different plants. We lucked the fuck out with bud - its trichromes are quite a bit of fun!
Trichromes serve two main purposes:
1) They are sticky and aid in catching male pollen. More trichromes = better chance of pollination.
2) THC absorbs UV-B light very well, acting as a veggie sunscreen. THC is produced in the trichromes.
(It is thought that the trichromes and cystolith hairs, which we will get to in a minute, on herb might also play a role in deterring animals from eating the plants by making them less palatable, however, anecdotal evidence suggests that many animals find bud to be DELICIOUS. Humans are included in "many animals".
)
This macro shot shows the different types of trichromes as well as tiny hairs (called cystolithic hairs - "hairs" whose cells contain mostly calcium carbonate).
The red arrow points to a cystolithic hair. Note: cystolithic hairs are not the little red hairs we all know and love. Those red ones are way bigger than cystolithic hairs, which, in cannabis, at least, are unicellular.
The yellow arrows point to bulbous glands, which are very, very small (2 to 8 cells big), and contain minimal amounts of cannabinoids. They are one of three types of glands.
The blue arrows point to capitate-sessile glands, which eventually mature into the third and last type of gland: capitate-stalked, which are indicated by the green arrows.
In this photo, you can see the tops of capitate-stalked glands, and perhaps some capitate-sessile glands. The bulbous glands are too small and too blurred-out to see in this photo.
Capitate-stalked glands are what most people refer to as trichromes. At the bottom of these glands are various phenols and turpenes, which are precursors to cannabinoids. The "head" of the capitate-stalked gland contains the cannabinoids. Gland age and THC content are directly related (older = more THC). As the phenols and turpenes are moved up the stalk and into the "head", they are progressively biosynthesized into cannabinoids: first to CBG, then CBG > CBC AND CBG > CBD, and finally, CBD > THC. CBN, the compound which THC primarily degrades to, forms only after the plant has died. The image below shows the biosynthesis progression.
1 = CBG (cannabigerol)
2 = CBD (cannabidiol)
3 = CBC (cannabichromene)
4 = THC (delta-9-tetrahydrocannabinol)
These glands grow up to half a millimeter tall. They are the ones you want, and they grow all over the aerial parts of the plant (anything above ground).
Here's a good read from the UN's Office on Drugs and Crime: LINK
And the wikipedia article on trichromes: LINK
Indica vs Sativa and Different Highs
So why do different pots have different effects? It has to do with the ratio of CBD and THC at the time of harvest. Most of the effects of herb are attributed to THC. When CBD (which has little to no effect on its own) is taken in conjunction with THC, it adds sedating and euphoric qualities to the high.
The time it takes a sativa plant to reach maturity is quite a bit longer than the time indica requires (once flowering has begun, 10-16 weeks for sativa compared to 6-8 weeks for indica). This makes all the difference in the high! Scroll back up to the graphic depicting the progression of cannabiniods. The longer a plant is alive, the longer its resin glands have time to take the steps to get from CBG > CBD > THC. Thus, as time goes on, the ratio of THC to CBD increases (meaning more THC and less CBD). This also means that plants that reach maturity faster have a lower ratio of THC to CBD (meaning less THC and more CBD).
Putting it all together...
Since sativas take quite a bit longer to reach maturity, they have more time to build up THC and have less CBD. This gives sativas a cerebral, psychedelic, and stimulating high - trippy buds.
Indicas, on the other hand, reach maturity much sooner than sativas, and so have less time to build up THC and have more CBD, giving indicas an extra bit of euphoria and sedation - couchlock buds.
For example, a sativa plant might have a THC:CBD ratio of 3:1, while an indica plant might have a THC:CBD ratio of 1:2.
Ah, and then there is ruderalis, which, it appears, has high levels of CBD, but no THC (or at least very, very little - not enough to get you high at all). Somebody with access to ruderalis ought to do a butane extraction and mix in some of the resultant oil with a bowl of straight sativa to see if the high is sedating instead of stimulating.
Another cannabinoid which is found primarily in Indian, Nepalese, S. African, and Afghani indicas is tetrahydrocannabivarin (THCV). THCV actually antagonizes (reduces, in this particular case) the effects of THC. This could possibly increase the sedating and euphoric effects of indica pots from these parts of the world, which are the varieties from which hashish is traditionally made.
Hope that clears a few things up!

There seems to be an ungodly amount of confusion over THC, its physical location in the cannabis plant, and the purpose of it / trichromes. I hope this post will help out those not in the know to figure out what's going on with THC and trichs.
Trichromes and Cannabinoid Production
Trichromes are glandular hairs which are found on many different plants. We lucked the fuck out with bud - its trichromes are quite a bit of fun!

Trichromes serve two main purposes:
1) They are sticky and aid in catching male pollen. More trichromes = better chance of pollination.
2) THC absorbs UV-B light very well, acting as a veggie sunscreen. THC is produced in the trichromes.
(It is thought that the trichromes and cystolith hairs, which we will get to in a minute, on herb might also play a role in deterring animals from eating the plants by making them less palatable, however, anecdotal evidence suggests that many animals find bud to be DELICIOUS. Humans are included in "many animals".


This macro shot shows the different types of trichromes as well as tiny hairs (called cystolithic hairs - "hairs" whose cells contain mostly calcium carbonate).
The red arrow points to a cystolithic hair. Note: cystolithic hairs are not the little red hairs we all know and love. Those red ones are way bigger than cystolithic hairs, which, in cannabis, at least, are unicellular.
The yellow arrows point to bulbous glands, which are very, very small (2 to 8 cells big), and contain minimal amounts of cannabinoids. They are one of three types of glands.
The blue arrows point to capitate-sessile glands, which eventually mature into the third and last type of gland: capitate-stalked, which are indicated by the green arrows.

In this photo, you can see the tops of capitate-stalked glands, and perhaps some capitate-sessile glands. The bulbous glands are too small and too blurred-out to see in this photo.
Capitate-stalked glands are what most people refer to as trichromes. At the bottom of these glands are various phenols and turpenes, which are precursors to cannabinoids. The "head" of the capitate-stalked gland contains the cannabinoids. Gland age and THC content are directly related (older = more THC). As the phenols and turpenes are moved up the stalk and into the "head", they are progressively biosynthesized into cannabinoids: first to CBG, then CBG > CBC AND CBG > CBD, and finally, CBD > THC. CBN, the compound which THC primarily degrades to, forms only after the plant has died. The image below shows the biosynthesis progression.

1 = CBG (cannabigerol)
2 = CBD (cannabidiol)
3 = CBC (cannabichromene)
4 = THC (delta-9-tetrahydrocannabinol)
These glands grow up to half a millimeter tall. They are the ones you want, and they grow all over the aerial parts of the plant (anything above ground).
Here's a good read from the UN's Office on Drugs and Crime: LINK
And the wikipedia article on trichromes: LINK
Indica vs Sativa and Different Highs
So why do different pots have different effects? It has to do with the ratio of CBD and THC at the time of harvest. Most of the effects of herb are attributed to THC. When CBD (which has little to no effect on its own) is taken in conjunction with THC, it adds sedating and euphoric qualities to the high.
The time it takes a sativa plant to reach maturity is quite a bit longer than the time indica requires (once flowering has begun, 10-16 weeks for sativa compared to 6-8 weeks for indica). This makes all the difference in the high! Scroll back up to the graphic depicting the progression of cannabiniods. The longer a plant is alive, the longer its resin glands have time to take the steps to get from CBG > CBD > THC. Thus, as time goes on, the ratio of THC to CBD increases (meaning more THC and less CBD). This also means that plants that reach maturity faster have a lower ratio of THC to CBD (meaning less THC and more CBD).
Putting it all together...
Since sativas take quite a bit longer to reach maturity, they have more time to build up THC and have less CBD. This gives sativas a cerebral, psychedelic, and stimulating high - trippy buds.
Indicas, on the other hand, reach maturity much sooner than sativas, and so have less time to build up THC and have more CBD, giving indicas an extra bit of euphoria and sedation - couchlock buds.
For example, a sativa plant might have a THC:CBD ratio of 3:1, while an indica plant might have a THC:CBD ratio of 1:2.
Ah, and then there is ruderalis, which, it appears, has high levels of CBD, but no THC (or at least very, very little - not enough to get you high at all). Somebody with access to ruderalis ought to do a butane extraction and mix in some of the resultant oil with a bowl of straight sativa to see if the high is sedating instead of stimulating.
Another cannabinoid which is found primarily in Indian, Nepalese, S. African, and Afghani indicas is tetrahydrocannabivarin (THCV). THCV actually antagonizes (reduces, in this particular case) the effects of THC. This could possibly increase the sedating and euphoric effects of indica pots from these parts of the world, which are the varieties from which hashish is traditionally made.
Hope that clears a few things up!

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