Hi, Leigh. That's a sagittaria subulata aka dwarf sag.
Thanks. I had wondered if it might be, but I have another plant that's
supposedly S. subulata, and it looks very different. It's much shorter, and a
much lighter green. It also grows a lot slower. A natural variation in the
species?
Leigh
http://www.fortunecity.com/lavender/halloween/881/