That is correct Corvus, not submersible... they were well below the old water line but when I went back to the pond I realized that where I found them had been drained since the tail end of last summer so they had some time to seed there so to speak.
They were kool while they lasted, and Yes , they would be very nice in your pond's edges, I have found a patch down the road that is growing at the edges of a small pond with the foliage half out of the water... its 14 " Tall and a rich green color. Would be an awesome terrarium plant too.
But hey, thats the fun of trying natives, ya just never know how it will respond to OUR conditions which are very different then their natural lighting and ferts.
Concentrate on marshy areas at your local ponds... it seems to like still water.