Ruppia cirrhosa

Ruppia cirrhosa is a species of aquatic plant known by the common names spiral ditchgrass and spiral tasselweed. It is native to Europe and western and Central Asia from Portugal and the British Isles to Scandinavia, the Altai, and Iran, India, eastern Asia from southeastern China to the Russian Far East, North Africa, southern Africa, western and central North America, and northern Argentina. It grows in freshwater bodies, such as lakes. It is a thread-thin, grasslike perennial herb which grows from a rhizome anchored in the wet substrate. It produces a long, narrow inflorescence tipped with two tiny flowers. As the fruit develops the peduncle of the inflorescence curls into a neat spiral....read more on Wikipedia.