what happens when a plant is subjected 2 low humidity?

just curious to what the title says.

i have heard that, low humidity could cause thin leaves. and i have seen to what i was told the reason for some of the west coasts biggest trees were results in high humidity.

bump!

does this have any major affects? how about during flower?

i also heard it causes narrow leaves. i also heard it cause the plant to make extra resin. i read that some where i forgot where.

real low humidity would probably make your grow room really dry, i think you want 40-60 % humidity