The trichomes are what contains the THC. It's by these that you can tell when your plant is ready to harvest. It's what makes the plant look "icy". Some people say that when 75% of the hairs turn amber then youre ready to harvest but they have nothing to do with the potency. The trichs do. If you really want to see trichs get yourself at leat a 30x microscope (jewelers loupe)