Just because a few dumbbells abuse a plant that looks like industrial hemp is no more reason to place draconian restriction on the cropt than is jailing every male between the ages of 15 and 30 who isn't gainfully employed or enrolled in education because this is the group which disproportionately commits crime.
My question is, what in the Constitution gives the Feds authority to prohibit farming of this crop, provided the state has approved it?
Yep. From what I've heard you'd have to smoke a few acres of industrial hemp to get a high and by that time you'd have a headache that would kill a bull elephant.
There are numerous differences between industrial hemp and marijuana. First, industrial hemp is, I believe, the male plant. Second, the stalks are allowed to grow to enormous heights where marijuana is forced to remain smallish. And third, industrial hemp plants are grown very close together where marijuana is supposed to be grown so many feet apart.
It's a shame that hemp must be purchased from Europe, Canada, and China to be made into fine clothes that last so much longer than cotton.