Yup, and it works.

Actually it works well. If a leaf breaks off without any stem (and we have all done that) just gently plant it and take care of it the same way and you should get babies!!! Rosie

You can also cut away some of the lower leaf to /make/ a new stem out of the center vein and then plant it as if it still had a stem. That still works fine. Alternatively if it's a large leaf, you may cut it up and put down the parts and all of the pieces, if reasonable size, and they'll make babies too as long as you put them cut vein side down.

The center vein is actually the root .

The center stem is not root tissue. They have a different cellular structure. There is also more than one kind of roots. For example, you get a different kind of root system if you start leaves in water than you do in soil, and you need to take care transitioning a plant from one to the other.