If built a few stained things out of poplar (not trim) and really like it but you have to pick through the pile. I have seen boards where the heartwood is purple.
I can't see how green or any other wood colouration would go away with stain. The stain will be affected by any underlying wood variations, such as growth rings, water damage, etc.
I agree with Lenaitch...We built Two curios out of poplar and the mantle between
our LR & DR is poplar ( stained dark) However, it is difficult to get a good
stain job. We also made another cabinet with poplar and I couldn’t get the
stain to my liking, so I gave away the cabinet. We avoided all the poplar
that had green in it. But, it’s a matter of taste, I like it clearer.
We also used poplar for window
trim and mantels in our family room - that I stained white with a dollop of
dark stain mixed in to get a beige hue to match the beige walls.
To arcticranger...What kind of doors are you trimming? stained or painted?
We put the (white stained)window trim in about 15 years ago and have
not had to do anything to it except dust it.