Hi Judith Truly,

I live on a riverbank. The river floods two or three times a year and
planting area will stay under water sometimes as long as four or five
days.
I want to find some flowering plants (nothing to cut off the river view)
that will tolerate such conditions. It's fairly shady as there are two
huge
sycamores on the bank.
I will suggested you have a walk along the riverbank, and see if something
growing there are what you like, than either get it from the owner or
nursery.
Sometime plant died not because can't tolerate the covering of water, but
may be the PH of the water at that period. e.g. salt water cause by high sea
level.

Regards,
Wong