This has been posted before on this forum, but not by me. I let my tiger lily dominate the surface of my 220g tank, covering maybe 2/3 of the 6' x 2' surface. This shaded everything and caused other plants to suffer (which is why this is a one time occurrence in this tank), but the lily was happy with this arrangement and sent up two flowers. The second and more glorious one is here:
When I took those pictures yesterday, I had already removed most of the leaves from the surface. The bloom opens at night and slowly closes during the day.