Wood species on Poul Jensen chair  

Telltale medullary ray flake suggests stained beech.

What tktoo siad but strike suggests and replace with unequivocally indicates.

Thanks guys. I had a feeling with the yellowish tint to the frame.

P.s. Leif, you have lost me.

Cheers!

Leif just said it's definitely beech, not just probably beech.

The little short rays visible in the photo of the leg are the tip-off, as tktoo said. They are denser areas of the grain that do not absorb stain very well, which makes them easy to spot. You won't see them on every piece of beech, only boards cut at a certain angle from the log (I think "quarter sawn" but don't quote me).

... and while the photos are not very sharp, it looks like it may not be the original finish, with someone previously trying to replicate the original walnut stained finish.