It's just like a wapato only it's not an arrowhead. Only difference is that it's leaves taper back down at the petiole.
Much more details needed!
I can look in my copy of "The Genus Arum" by Peter Boyce in order to help ID this Arum.
The flowers look like this but it's NOT a wapato. At least the leaves arent arowhead shaped. In all other ways it looks exactly like one.
I don't think that's an aroid. My understanding is that all aroids have some variation on the spathe and spadix form for the inflorescence. (I started to say 'blossoms' but while your picture shows 'blossoms' the actual 'flowers' on an aroid are little things on the spadix.) You might try the 'Name that Plant' forum if you don't get an answer here; those folks are really amazing!
Almost looks like a trillium to me.
I pointed this out to my son, who just moved here from Seattle. He pulled out his 'Flora of the Pacific Northwest', and it appears this may be the 'arum-leaved Sagittaria', S. cuneata. So it's possibly 'almost' an arum!
Alot of Sagittaria have saggitate leaves...hence the name. Not an Aroid but a great, Aroid-looking genus nontheless.
Yep! That's it!
Pity it's not an aroid though.
Okay,now for the next question. Think this thing will be okay fully submerged in my kiddiepool?
I've got the answer to my question now. It seems that when you fully submerge this creature it sloughs it's "above water" leaves in order to grow an entirely new set that appear far more straplike and looks strangely like something one might purchase at an aquarium shop.
I'm so glad you posted this follow-up! It's nice to hear how things work out.