birthroot(n = noun.plant) purple trillium, red trillium, trillium erectum - trillium of eastern North America having malodorous pink to purple flowers and an astringent root used in folk medicine especially to ease childbirth;
is a kind of trillium, wake-robin, wood lily

   An herbaceous plant (Trillium erectum), and its astringent rootstock, which is said to have medicinal properties. [1913 Webster]