I'm interested in what people think this might be. It arrived labelled A. davidii 'Karmen', but since that's obviously not so ended up being a "free addition" to the garden. Fall color is yellow/orange, quite showy. There is no bloom on new stems. Flowers are typical of a macrantha type, yellow green in long racemes. Pictures are: overall aspect; base; mature leaves; samaras; interior bark; new growth. Anyone willing to "go out on a limb" for a positive ID? I have my own ideas but will keep stum for now.