Irises aren't aquatic, they're what's known as marginals, which means the boggy, damp edges of a natural pond - the two that like these conditions are cultivars of Iris laevigata or Iris pseudacorus.

Yellow flag iris psuedocorus can go directly in a basket into the water. I have it in the pond and it grows into the water of leven canal and the river hull.

Oh okay, so much for the info in the books then, Seaburngirl, which says quite clearly its a marginal, lol

they start off in the margins when the seed floats into the edges but the rhizome is very stiff.Many marginals can support a floating mat of roots that then collects soil/humus leading to the infilling of waterways over time. If you look at my pond pictures you will see what I mean. both clumps started in a 10" basket. So yes they are marginals as they wont start in the middle of a lake. :o) [didnt mean to sound as if i was contradicting you bamboo]

I don't mind being corrected at all, Seaburngirl - it's another useful way of learning, if the corrector is well informed - which you are!

well thats two of us. :o)
Just take the grey/white stuff on the acer I could have sworn it was a foliose lichen.

Ha ha, Seaburngirl - probably personality difference - I always expect the worst, you always look on the bright side, lol