I have an oakleaf hydranga that I successfully got two babies from, just already coming up as described from the ground, Moved them to other locations, and they are now there 3 years or more, and 5 foot tall. there is also another one, I got two babies from, and the same, it gave up babies one at a time. Now I have two more in other places. Back to my oakleaf, there is one good size one there now again under the original mom. Left it there, husband says he may want it somewhere, its been there two years now, just getting bigger.
the shrub Clethera, will root up babies also (hope I spelled that right) close enough. have many there near the mom, ready to toss them though. Also my Japanese Maple, reseeds babies, I have gathered several and potted them up in nice soil to grow taller.