Uh, do you mean house plants?

There is also a Ted talk about taking this to an extreme, which does seem to anecdotally work: https://www.youtube.com/watch?v=gmn7tjSNyAA&pp=ygURdGVkIGthb...

House plants do reduce the amount of CO2 in your home but not by as much as you'd hope.

The most efficient system is algae, but you require a pretty massive amount of it to compensate for the amount of CO2 a single person emits.