TolkienFan I just wanted to give you a more exact identification for the first pic in this thread. People have called it poplar, but that's probably regional. Lots of different trees are called poplar depending on where you're from -- for instance, here in Vermont the Eastern Cottonwood (Populus Deltoides) is called "poplar." It is truly in the poplar family genus (Populus). The wood is light colored relatively weak, split and warp prone when I've tried to use it for making things after sawing in my mill.
The tree in your first photo is actually so-called "yellow poplar" or "tulip tree", Liriodendron tulipfera, It is not a true poplar (Populus) at all. It's outward charactersitics are very different than the true poplars. The leaf is shiny and mitten shaped instead of oval, dull, and sawtoothed. The trees are tall and very straight, and the bark and flowers are very different.
I don't know if it is a good wood for bows, but I do believe it's a better wood than the real poplars for other uses, so there may be some confusion about whether "poplar" is usable, depending on what actual tree wood was tried. Just saying, maybe not rule it out just yet unless someone knows for sure about Liriodendron, and not Populus.