Yellow poplar makes good arrows, not a good bow wood. Green ash will make a bow, but it's not nearly as good as white ash. I've seen some nice sweetgum bows-it apparantly makes a good bow but isn't used much, probably because it's so hard to split. Keep an eye out for osage orange, black locust, elm, black walnut, hackberry, flowering dogwood, persimmon, hickory, and white oak. There are a lot of good bow woods out there waiting to be discovered. In general, most of the better bow woods are hard, dense, and heavy.