Evolution of Trichomes
Biologists have a hypothesis that trichomes evolved as a defense mechanism of the cannabis plant against a range of potential enemies . Trichomes, from the Greek meaning ‘growth of hair,’ act as an evolutionary shield, protecting the plant and its seeds from the dangers of its environment, allowing it to reproduce. These adhesive sprouts form a protective layer against offensive insects, preventing them from reaching the surface of the plant. The chemicals in the trichomes make cannabis less palatable to hungry animals and can inhibit the growth of some types of fungus. The resin also helps to insulate the plant from high wind and low humidity, and acts as a natural ‘sun-screen’ in protecting against UV-B light rays. But since trichomes contain euphoric properties attractive to humans, it may be man who has had the most influence on the plants’ development through many years of favoring strains that consistently produce more of these gooey resin heads.
Inside the Trichome
THC and other cannabinoids including terpenoids are produced inside the heads of the trichomes. How it happens: Organelles produced by the plant called Vacuoles – which contain phenols, a chemical compound similar to alcohol, and another type of organelle called plastids – containing hydrocarbons called terpenes, make their way up the trichome stalk and combine inside the secretory cavity into a fibrous mat. This concentrated mat is hit by UV-B light waves, causing the creation of cannabinoids. Since all of the psychoactive ingredients are produced inside the trichome, these tiny resin hairs have long been sought after by hash and oil makers and can be separated from the plant and harvested in a variety of ways. 
Potency and Trichomes
Many people say the ‘potency’ of today’s pot has increased dramatically in the last 30 years. Which may or may not be true. It is hard to say because testing methods of today did not exist in the olden days of Cannabis breeding. When seed Banks and breeders label Cannabin varieties as 20%, or even 30% THC, they are not reffering to the % of the entire plant, it is measured with Gas Chromotography, and it is a Percantage compared to the other active compounds in the smoke. Meaning, 30% of the active compounds in the smoke are THC, not 30% of the 1 gram bud is THC. One thing is for sure; heavy trichome production does not necessarily mean higher potency, because the resins inside the trichome may or may not contain high levels of THC and other active ingredients. Some speculate that the percentage levels refer to the amount of THC in the oils produced inside the resin glands, but new studies show that cannabinoids other than THC also have distinctive effects on brain functions and cause correspondingly different effects on human cognition and psychiatric symptoms. This makes gauging the ‘potency’ or ‘strength’ of cannabis plants very difficult, as different cannabinoid level combinations may induce different types of highs.