Hippuris vulgaris
Template:Short description Template:Distinguish Template:Speciesbox Hippuris vulgaris (from Template:Langx – horse and Template:Lang – tail), known as mare's-tail<ref name=BSBI07>Template:BSBI 2007</ref> or common mare's-tail, is a common aquatic flowering plant in the family Plantaginaceae. Its distribution ranges from Eurasia and North America to Greenland, the Tibetan Plateau and Arizona. It prefers non-acidic waters.
Description
The common mare's tail is a creeping, perennial herb, found in shallow waters and mud flats. It roots underwater, but most of its leaves are above the water surface. The leaves occur in whorls of 6–12; those above water are 0.5 to 2.5 cm long and up to 3 mm wide, whereas those under water are thinner and limper, and longer than those above water, especially in deeper streams. The stems are solid and unbranched but often curve, and can be up to 60 cm long. In shallow water they project 20–30 cm out of the water. It grows from stout rhizomes. The flowers are inconspicuous, and not all plants produce them. Studies of H. vulgaris in the Tibetan Plateau have shown that it is a prolific methane emitter.<ref name="Hirotaetal2004">Template:Cite journal</ref> The roots of H. vulgaris extend into the anoxic zone of wetland soils and create a conduit for methane produced in the anoxic zone to travel to the atmosphere.Template:Citation needed
Uses
It can also be a troublesome weed, obstructing the flow of water in rivers and ditches.Template:Citation needed