Mark,
I finally duplicated the problem...sorta:
Bush first then tree...ok. Copied bush...bad. Tree then bush...bad. Copied tree over all bushes...ok.
???
But all is fixed if the tree png transparency is changed from 98 to 100.
Also, my trees and bushes (in fact, all textures) will look better if you turn off "allow anti-aliased textures"...SU remains lousy at anti-aliasing.
Best, Tom.
No, unfortunately, if I try to rename the .skm file in the application support library location, it reverts to its original name on reopening SU, as well as to the original material properties. If I rename the material in the edit field in SU, it retains the new name, but not the edited properties on reopening.