Shoreweed (Littorella uniflora)

Shoreweed (Littorella uniflora)

Observation - Shoreweed (Littorella uniflora) - UK and Ireland. Description: This plant is normally underwater but has been exposed during the recent dry spell. The leaves are short - a couple of inches / 5cm - and circular in cross-section. Help with an ID would be appreciated. Edit: Changed to match Tim's ID. Many thanks.

This plant is normally underwater but has been exposed during the recent dry spell. The "leaves" are short - a couple of inches / 5cm - and circular in cross-section. Help with an ID would be appreciated.
Edit: Changed to match Tim's ID. Many thanks.