What is "butterfly weed"

Pleurisy \Pleu"ri*sy\, n. [F. pleur['e]sie, L. pleurisis, pleuritis, Gr pleyri^tis (sc. no`sos), fr. pleyra` rib, side.] (Med.) An inflammation of the pleura, usually accompanied with fever, pain, difficult respiration, and cough, and with exudation into the pleural cavity. Pleurisy root. (Bot.)

1. The large tuberous root of a kind of milkweed ( Asclepias tuberosa) which is used as a remedy for pleuritic and other diseases.

2. The plant itself, which has deep orange-colored flowers; -- called also butterfly weed.

n. erect perennial of eastern and southern United States having showy orange flowers [syn: orange milkweed, chigger flower, chiggerflower, pleurisy root, tuber root, Indian paintbrush, Asclepias tuberosa]