Fancy Saplings Change(Decorations)

You know almost all tress give Saplings from the leaves. But you know leaves aren't the baby phase of the tree the baby phase would be the seed! Soo! How about when we plant sapling we got 2blocks tall "bush" or "young tree" which is sapling while it's still act the same as before can't grow if there block above which block it's grow phase & the texture of the Saplings remain same even in flower pot but different when planting...(I has a lot of ideas connected to this but I would only suggest this since I shouldn't list things up)