Have just googled images of Pennisetum glaucum and come up with 'Purple Majesty' & 'Purple Baron' and they do look remarkably close to our mystery grass. BTW, I see it's also called 'Ornamental Millet' so it looks like you are both correct...thanks for the suggestions : ¬ )

Having a picture of the flower/seed head would definitely help. This may be a sedge (Carex) rather than a grass.

Hansie, Thanks for your input! It is definitely stiltgrass...physical description matches AND the deer won't eat it! I can't bring myself to go the chemical route. This property is wild...early spring there are ephemerals...these get going way before the stiltgrass. Then there are patches of sedge, goldenrod, dogbane etc that I assume over time would maybe...hopefully...become stiff competition for the stiltgrass. Before I knew what this stuff was I was pulling it out and removing it....worst thing I could have done....spread seeds all over AND left bare dirt. This fall I have left the stiltgrass in place, bought all the mulch I could afford, collected coffee grinds, cardboard, leaves....anything I could find and I am covering all the worst patches w/this. My understanding is that the seeds are very small and require light to germinate. They also don't like rotting substrate....so if I can "smother" the bulk of seeds then maybe what does come up will be more manageable. I understand that w/all this smothering some other plants may be affected but in my experience they won't be killed just set back a bit and maybe not at all if we get enough rain to rot all this stuff down. I just wish I could hear from someone else who may have attempted smothering w/stiltgrass...have you ever tried this method?

looks like what i call quack grass ... see link at the appropriate search engine.. lol ... that said.. i guess based on what i know from my MI garden.. im not here to argue with the botanists ... we might need to see it flower ..... ken https://duckduckgo.com/?q=quack+grass&t=ffcm&ia=web