I noticed that not all grass stems seems to be used for reproduction. When growing freely, it seems there are two heights of grass: there's the main ground-cover (stolon or tillers, maybe?), and there's the tall stems that distribute pollen and seed (looks kind of like wheat/grain/cereal, I guess). I don't know if it's a polymorphism or if perhaps the two are simply a generation apart. My question is, what are the taller, stronger, reproductive stems called?
Like the tall grass on the right, here. It's all tall compared to the mown lawn on the left, but you can see some is taller, and in this case kind of brown/yellow.