Ornamental sedge/grass ? what

Ornamental sedge/grass ? what

Observation - Ornamental sedge/grass ? what - UK and Ireland. Description: Growing by garden pond. Also which is the male and which the female parts? I've added a couple more detailed photos. The leaves are variegated and the stems round, presumably a grass then.

Growing by garden pond. Also which is the male and which the female parts?
I've added a couple more detailed photos.
The leaves are variegated and the stems round, presumably a grass then.