Knotgrass is one of the most resilient of all plants – a born survivor. It will grow in any kind of crevice as well as in sand, including coastal sand dunes, where it weathers the salt spray.

The Latin description tuberosus refers to the underground tubers that grow from the roots of the Earth-nut Pea and serve as storage organs. As soon as it germinates the young plant produces small branching rootlets.

Later round to oblong tubers appear at the points where the roots branch, increasing in size as they grow. It takes about four years for these to be fully developed and ripe. Dark and firm on the outside and practically pure white inside, they contain many reserve starches and sugars.

Although somewhat bitter in the raw state, the tubers used to be a favourite food of poor country children who pulled them up from the ground. Or they were cooked and eaten, roasted and used as a coffee substitute, or fed to the pigs. These tubers were likewise used as a home remedy for checking diarrhoea.

The flowers of plants of the buckwheat family (Polygonaceae) are usually arranged in whorls of three. Knotgrass is an exception: its flowers are arranged in a spiral. The sixth floral envelope ceased to exist in the course of evolution. The stems of Knotgrass may be creeping, prostrate, or ascending. The leaves are of interest for their nocturnal movement; they lift and press together for the night. The achenes used to be used as bird-food, and this accounts for the specific name aviculare.

There are marked differences between separate populations of Knotgrass. This is a plant which often forms thick spreading carpets and stands up well to heavy usage. It therefore serves as a useful substitute for turf on playing fields and airfields.