Ah, the question that will never die
Bows can and have been made from poplar, but it's very marginal as bow wood and you're probably just setting yourself up for disappointment if you try it. If you do try it, make it very long and wide, and I would back it with sinew. People seem to like to try to make bows from poplar as a challenge, but they usually seem to self-destruct pretty quickly and unexpectedly. If you're referring to tulip poplar, it makes excellent arrows, though..