as i've heard it, true canes can't be started from just a leaf. there are a lot of shrub type begonias that have the "angelwing" shape, however, that have been grown slowly from leaves.

-ming

You're absolutely right, Ming--I think a lot of us have heard you couldn't grow a cane from a leaf and tried it anyway, but found it was true. There are some with mixed heritage, like shrub/cane crosses, that look like canes and will grow, as you say, slowly from leaves, but I don't believe any true canes will. But they're so easy from stem cuttings we don't need to root from leaves!