Poplar, which is not a poplar.
Above a freshly cut piece of wood that had been outside. It is what in lumber yards would be called Poplar, white or yellow, though it is actually a Tulip tree. It is also called Popple. Normal color is white or green as the example above shows, turning brown upon exposure. Sometimes a fresh cut will reveal a variety of colors, purple, red, black; from mineral staining. Called Rainbow Poplar when so colored.
A good choice for moldings to be painted, as in architecture; not used that much in framing. The piece above came from a scrap pallet that was mostly oak, destined for the wood stove/fireplace, when I saw the green. Also used as a secondary wood in furniture, where it can also be used as the primary, stained and finished as cherry.
The botanist's identification of wood is often at odds with the lumberman's.