Guessing the Sex of Ginkgo Biloba

I've heard from some people saying that you can tell the sex of the trees by looking at the leaves. They say that if the leaves have a small split, it's a female and if there isn't a split, it's a male. Is this true?

I have not heard of this and since there are no mature trees in my vicinity I cannot even see if it may be true for some plants at least. As far as I remember all of our ginkgos in our greenhouse had split leaves, but if the splits were of different depth I cannot recall. They are bare now, since it is December.
I have heard that male trees tend to grow narrower and taller, while female trees grow wider and shorter. This makes sense, since the males want to disperse their pollen as far as possible and the females want to have as big a receptive area as possible. But environmental conditions can play havoc with this generalization as well.