In my web wanderings, I read some British cat explain that the distinguishing characteristic of phalaris grass was the little collar (forgot the real name) where the grass blade starts to shoot out of the stem. This part is normally hidden, having a sheath of green stuff wrapped around it, holding the blade to the stem. But when you pluck it out, you can see vertical striations, like pinstripes, on phalaris grass. It's very tiny, evidently only about 1/8 inch high, so it needs very close inspection. Now this isn't from personal experience, this is only my memory of what somebody else said, but there's a possibility it might help you. It was what I was keeping in mind, in case I found a phalaris grass candidate; hope it's accurate.
turning science fact into <<science fiction>>