This little tropical grass feels at home in Perigord, and more and more also in other places. Water Finger-grass (Paspalum distichum) grows in wet places where the water level changes often, as here in a dead river branch of the Dordogne.
It is considered as a pest because it can cover a large surface in a short period, thanks to its runners that, well, seem to run. It grows so fast other wetland plants can't compete with it. It does not survive cold weather, but last winters haven't been that cold. Ducks, (mallards and other wild duck species) eat it, anyhow.
It is easy to recognize when in flower, and its flowering season goes on from early summer until November. Every stalk carries two ears, each with dark red pistils and stamina.
The sheaths of new leaves are flattened and sometimes reddish with long white hairs. There is no membraneaous appendice - a ligule - where the sheath ands and the leafs begins
.