Leaf propagation is a really cool propagation method that every beginner gardener should at least try once because it is like watching a science fiction movie come to life; you can actually see little plantlets emerging from the mother leaf and developing their own support system, the root system.
Stems that are attached to their parent plant are capable of forming roots on coming in contact with a rooting medium. Layering exploits this property of stems. It involves development of roots on a stem while the stem is still attached to its parent plant. A layer is the rooted stem following detachment from the parent plant.