Red-tipped grass

Here's what happens when you do not mow the lawn. I have a few such clumps. The red-tipped flowering heads are a kind of misicanthus variety of ornamental grass which I bought a few years ago. The all green huge clump is what naturally grows as lawn grass in this wet part of the garden. In fall or early spring I have to cut them down with an electric hedge trimmer.
They are easily 10 feet tall.