Asclepias tuberosa L. - Asclepiadaceae - butterfly weed, orange milkweed, pleurisy root, Knollige Seidenpflanze, Orange Seidenpflanze

Rough-hairy leafy perennial of North America, 60-90 cm high, from long horizontal roots; leaves alternate, lanceolate or oblong, acute or obtuse, sessile or very short petioled; flowers about 6 mm across, in short-peduncled many-flowered umbels; corolla greenish-orange; hoods narrowly oblong, orange or yellow, slightly longer than the filiform horns; follicles finely pubescent, erect on deflexed pedicles.

„In the 19th century plant parts were used for lung problems such as asthma and bronchitis. Asclepias tuberosa is still used in homeopathy as remedy.“ http://de.wikipedia.org/wiki/Asclepias_tuberosa

„The fluidextract of Asclepias tuberosa was found to contain substances estrogenic to castrate rats. A method for separating these substances is proposed. The fluidextract was also found to exert an appreciable oxytocic-like action upon the uteri of several species of laboratory animals both in vitro and in vivo.“
[The estrogenic and uterine-stimulating activity of asclepias tuberosa. A preliminary investigation. Christopher H. Costello, Calvin L. Butler, Journal of the American Pharmaceutical Association 39.4 (1950): 233-237]

„Sixteen glycosides of pregnanes, including ikemagenin, lineolon and a new pregnane, pleurogenin, were isolated and their structures were elucidated. Since these glycosides foam to a lesser degree than spirostan or triterpenoid saponins, an expectorant effect can be expected when the roots are used to treat pleurisy or bronchitis.“
[Pregnane glycosides from the roots of Asclepias tuberosa. Abe, Fumiko, and Tatsuo Yamauchi. Chemical and Pharmaceutical Bulletin-TOKYO- 48.7 (2000): 1017-1022] http://cpb.pharm.or.jp/cpb/200007/C07_1017.pdf

Magazine of botany and register of flowering plants [J. Paxton], vol. 2: p. 26 (1835-1836) [F.W. Smith]
http://plantgenera.org/species.php?id_species=96837