Ya know, when I was a teen it was believed by all my friends, who'd gotten the info from an MJ authority, that you told the sex of the plant by counting the pucks on the leaves. If it had 5 pucks it was male and if it had 7 it was female. Or possibly the other way around, It's been a while so I don't recall clearly. The point is that this way something that everybody who knew anything about pot knew. The people that I'm talking about didn't even know it was the buds that you smoke. They thought it was the leaves, as did I because I knew as little as they, but they were authorities and would tell anyone who would stand still long enough.

My guess is that someone who's ignorant of MJ thought that chart up and it's now become an urban ledgend, like counting the pucks, because people who don't know squat about the subject are always trying to make shit up to sound like they know everything.