I have had several calls and have received a few samples of what people describe as a foxtail-like weed growing in lawns that form clumps of grass that tend to shred at the tips when they are mowed.
These are Fountain Grass (Pennisetum alopecuroides). This is an ornamental grass that self seeds into lawns. It has a very tough blade that does not mow cleanly. It shreds at the tip. It also produces a foxtail-like seed head when mowed.
Here is a picture of Fountain Grass on a berm in my lawn and some of the surrounding patches. I also included a picture of a sample that I received last week from Keokuk.
How do you control it? Zac Reicher did a lot of work on this when he was at Purdue. The best way to kill it is Roundup, but this has to be done non-selectively. Quinclorac was the best postemergence selective material in his trials. For an article on this work, see the article by Voigt and Reicher, 2010:
Here is Fountain Grass used as an ornamental in my yard.
Here is Fountain Grass that has escaped into my lawn
Here is the sample from Keokuk.