Float grass, Glyceria fluitans
Our native float grass grows in wet soils and shallow water.
The seed can be used raw or cooked. A sweetish taste, the seed was considered a delicacy in some parts of Europe and was an article of commerce until well into the 20th century.
A flour from the seed is said to make a bread little inferior to wheat bread, the flour can also be used as a thickener in soups etc when it imparts a sweet delicate flavour.
Unfortunately, the seed is very small and therefore the plant is relatively unproductive.
The leaves have been burnt as an incense.