Are those weeds?

Tonight I was at a friend's house and looked over in her yard and said, "Are those weeds?"  [I'm rude.]  She replied, "It's a decorative grass that's gotten out of control."

My mom (an elementary school teacher) would say, "don't ask a child 'what is that?' when they show you a drawing or painting, but say, 'tell me about your picture.'"

So what I should have said was, "Tell me about that overgrown corner of your yard."