centaura wrote: I've heard that they are fiendishly difficult to propagate from seed.
Yes, the paperbark maple (A.griseum) is difficult to not only propagate from seed but cuttings as well. This is a freak maple of nature in that of the seed produced by the tree only 2% or less of the seed is actually viable with an intact embryo. Cuttings are also virtually impossible to strike. If you have a tree from which you can collect seed, get a bunch of them and you may get one or two to sprout. As far as a bonsai subject, they are rather difficult to make a real nice bonsai out of but if you have the patients and persistance give it a whirl. They have long internodes so cutting and pinching back is a constant job and makes progress slow. The smaller branches are rather straight and brittle which also makes if difficult to get nice movement in them. I tried a few of them and finally gave up knowing that there are many other more satisfactory trees to use.