I didn't know what a bulrush was until I looked it up just now, and it appears to refer to a few kinds of sedge and to baby Moses' papyrus basket. Sedges are pretty similar to grasses, but phragmites is definitely a grass.

According to the wikipedia article on phragmites, "Rhizomes of the plant are rich in N,N-DMT alkaloids," which I've never heard before. I suspect it's wiki-bunk, or else the fens would be full of college kids digging up the reeds' roots and smoking them.