I hate to jump in on this considering how it has been going and I really do not want to take 'the other guy's side' but most plants do have trichomes. Trichomes shade and cool plants and help control moisture loss and some are natural insecticides.The difference in trichomes on cannabis plants and others is others do not have THC/cannabinoid producing trichome heads. And to get a bit more detailed not every trichome head on cannabis plants has THC producing glands.
The most thoroughly studied case is the reflectant leaf type of
desert brittlebush (
Encelia farinosa), a desert perennial of western North America. Investigators have demonstrated that the
silvery leaves of late spring and summer are several degrees cooler than the same leaf would be
if it was lacking the silvery cover of trichomes (
leaf comparison). This is because
the trichomes reflect infrared radiation that causes heating of objects (just as it does in a microwave oven). Having a cooler leaf on a hot summer day in the desert permits the leaf to avoid reaching the high lethal temperature and, at the same time, reduces its loss of water vapor via transpiration because leaf temperature is lowered.
Additional Info:
Have you ever seen a hairy plant?
Plants may appear to have hair, but the technical term for plant hair is trichomes. These trichomes may resemble hair, but they’re not the same as what we mammals have.
Trichomes are not the same as our hair, but insofar as the definition of hair is that it is an outgrowth of the epidermis, then trichomes are for all practical purposes, a kind of hair. Unlike animal hair, though, trichomes are often living cells.
Trichomes can run the gamut in structure, appearance, and texture. Some trichomes are frail, some coarse; some are branched like tree limbs, others star-shaped; some are long and straight, others are short and curly.
Just as mammal hair serves various protective purposes, including insulation and camouflage, so do trichomes. Trichomes can be insulating by keeping frost away from leaf cells. They can help reduce evaporation by protecting the plant from wind and heat. In many cases, trichomes protect plants from herbivorous insects that may want to feed on them. And in some cases, if the trichomes are especially stiff or irritating, they may protect a plant from larger herbivores.