My friend's tongue

Hi everybody, I was driving today coming back home. My friend was

sitting next to me, and he was sticking his tongue out. He noticed that his

tongue has two main ( not black but rather grey or look green ) veins like

under his tongue. And you can say it's more like a tree veins.


He asked me if this is normal colour, and he was a little scared.

Is that normal? the two main veins with the tree of small veins are

distinguished colour from the red part of his tongue.

Thanks for any idea

It's my first I see such thing.