MARE'S-TAIL

mare's-tail, in botany, the popular name for an aquatic herb known botanically as _hippuris vulgaris_ (natural order haloragaceae). it grows on margins of lakes, ponds and similar localities, and has a submerged stout creeping rootstock from which spring many-jointed cylindrical stems bearing numerous narrow leaves close-set in whorls. the minute greenish flowers are borne in the leaf-axils. like many fresh-water plants it has a wide distribution, occurring in arctic and temperate regions in the northern hemisphere and reappearing in antarctic south america.