Bamboo

Hi All.
My wife was given this bamboo?? 2 years ago from someone at work. I have no idea what type of bamboo it is although to me it does not look like a typical bamboo. He did have it in the border and he said it just runs wild so he now has it controlled in pots.
Not so concerned what type it is but does anyone know if you either prune or just leave the plant. All the growth is last years and the stems that look yellow are not dead. Do not want to prune it back only to kill it.
Thanks.

 

It is perhaps one of the Sasa types.

Just my opinion.......
It will do better in the ground than in a pot.
If it is rampant, bin it. And try a Borinda or Fargesia which are more clumpling types

 

Thanks for you help & replies ,all opinions count,that is one way we all learn.