Hippuris vulgaris
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Clade:	Asterids
Order:	Lamiales
Family:	Plantaginaceae
Genus:	Hippuris
Species:	H. vulgaris
Binomial name
Hippuris vulgaris L.

Hippuris vulgaris (from Greek: ἵππος – horse and οὐρά – tail), known as mare's-tail^[2] or common mare's-tail, is a common aquatic plant of Eurasia and North America ranging from Greenland to the Tibetan Plateau to Arizona. It prefers non-acidic waters.

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.^[3] 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.^{[citation needed]}

It can also be a troublesome weed, obstructing the flow of water in rivers and ditches.^{[citation needed]}

Wikimedia Commons has media related to Hippuris vulgaris.

• Jepson Manual Treatment
• USDA Plants Profile