Any wood specialists here, such as Leif?  

I'm going with beech on this one.
The pronounced medullary rays visible on the end grain in the last photo are not seen in teak or walnut.

.
Thanks tktoo but beech has some other characteristics which don't exist.

Such as?
I'm not here to argue over opinions, onno. Just curious.

.
See figure, the characteristic small dark spots are missing.
But the more I look at the wood the more I think you could be right, maybe it's beech.
http://.

Yes, those spots are the same
medullary rays visible on the side grain adjacent to the end grain in your last photo. I think that the piece has been stained and has likely darkened some with age, too, so they are not as obvious as they would be on freshly cut material.

Looks like beech to me
though i'm not an expert. I've just seen a lot of beech. Plus, in your first photo it looks like tinted clear finish that has been wiped off in one spot, showing a more natural beech color.
The dark specks in the grain only show up on wood cut in one particular direction, as you can see in some of the photos on this page (which is from a great reference site, by the way). Look at the edges of the boards, specifically the 9th photo on that page.
there are also some great photos of the end grain.
http://hobbithouseinc.com/personal/woodpics/beech.htm

.
Well, seems to be beech in fact.
Thanks to both of you.

I concur with the others...
I concur with the others here: That is stained beech. The first two photos show the area around a large knot, which are going to show uncommon grain that will be harder to identify.
The third photo with the endgrain and sidegrain is pretty definitive. You can see the rays on the end grain. And on the side grain I can see the little dark flecks (which are the rays from a different angle as tktoo said). It has been stained so that the flecks are hard to see, but they form a sort of regular pattern, and if you look for that pattern it makes the flecks easier to see.

.
Thanks Leif.

Also I have learned that the...
Also I have learned that the fastest way to be wrong and have a big head about it is to have your opinion carry extra weight with your friends. So my opinion is just as questionable as anyone else's around here, maybe moreso. Especially when looking at photos of wood, which is a lying and deceptive medium

.
I see! 🙂