BURHEAD

any of the annual or perennial herbs of the genus Echinodorus (family Alismataceae), named for their round, bristly fruit. The plants grow mostly in warm regions in shallow ponds and swamps. They are slender and are seldom more than 25 cm (10 inches) tall. The leaves are spear-shaped or ovate. E. cordifolius, which has a creeping stem and large, ovate leaves, occurs in southern North America. E. tenellus has spear-shaped leaves about 5 cm long and occurs throughout eastern and southwestern North America, the West Indies, and South America. A number of species are cultivated as aquarium plants.