Pander Tree

Can someone please explain the joke behind the “Pander Tree”?
I know what “pandering” is, and I also know there is no real tree called a “pander tree”. So what is the story about this “tree”?

It’s a tree. That’s it. Tree shirts have been enormously popular in the derby in the past so using a tree could be seen as pandering. The exact same applies to bird silhouettes. This isn’t limited to woot.

Check out this shirt from urban outfitters:

Same idea.

ahh…

I see.

Sorry, but I’m new to the… um, shirt world…