Sunny roadcut. Appears to be escaping cultivation. Most plants were shrubs. A few were vining, growing sinistrorsely (rising from the lower right to the upper left).
ID is iNat's suggestion. On Panicum virgatum.
I had to go back and take photos of the undersides of the leaves because I somehow forgot to do that, so note that the final 4 images in this observation were actually taken 2 days after the rest of the images, but it's only 2 days, so I don't think it really matters that much.