Following up on this question, I took a few pictures today of the perennial ryegrass on our lawn. The lawn was last mowed five days ago. The stems grow thick and very fast, making the perennial rye visibly taller than surrounding fine fescue.
Overall view: notice how much taller the greener grass is than the surrounding.
Another angle: last week is hot, so some of the lawn has turned brown.
A close-up view: notice the height difference and the stemmy growth.
Further zoom-in: notice how the blades that were cut five days ago didn't grow, but the stems did.
Any reason why this is happening? Or is this simply due to inferior seeds? What types of rye grow like this?
UPDATE: A picture of the root.
UPDATE2: Pictures of seedheads.