Hmmm. The roots actually look like Spiderwort. I think the latin name is something like trancendentia. I've never seen a prolif on any I have grown though.
I just did a Google search for "daylily roots" then clicked on images. You might try that and see if the roots of what you have resemble the photos.
If I could touch it or see it in person, I am sure I could tell you what it was, but photos can be hard to tell.