Prickly pear

Prickly pear, any of a genus (Opuntia) of branching cactus with flat stems and yellow flowers. It is found in most of the southern United States and grows farther north (into New England) than other cacti. Prickly pears are grown in many places as hedges. Introduced to Australia, they spread so rapidly as to become a pest, but were brought under control by introducing a moth whose caterpillars burrowed into the stems.