I don't know if this is the same as our Reed mace(Bull rush) if it is it can
grow in up to 4 ft of water with us, and mine didn't start to throw the Mace
heads till 3rd year, the root seems to need to mature, and the plants
probably didn't feel threatened so no rush to reproduce.

--
David Hill
Abacus nurseries
www.abacus-nurseries.co.uk