Is this true

[orangeman]

My friend told me basically a cannabis LEAF, if you plant that it grows into a plant is this BULLSHIT? lol

Not a cannabis leaf but a cutting, or a clone. It needs proper care, not just slicing a cutting and throwing it in dirt and hope for the best. Cloning isnt a natural process therefore for it to work it requires human care. If you want to do this though first your gonna need a healthy plant .