Im a forester. Yet im a southern forester, and pine is mostly my thing as well as our local HW's. My first thought was cottonwood, before reading all the others. BUt i dont get much exposure to cottonwood (i see it from time to time) Ash or large elms here. I dont think sassafrass gets that big, like MOss said (at least i have never seen it around here that size?).