Yellow Flag (Iris pseudacorus)

Also known as Yellow Iris.  These we were given from a wild patch in a friends garden soon after we moved here.  Being a native flower they are good for pollinators.   In fact in a survey by the AgriLand Project it came out as second for nectar production per flower per day.

The plant is poisonous (roots and leaves).  Also it is an indicator plant or helps to indicate pH as it can withstand quite low pH and a fair degree of salinity.