English name: Asclepias.

Synonyms:  Pleurisy Root, Butterfly Weed Root.

Botanical origin:   Asclepias tuberosa L.

Impurities: Not more than 5% of foreign matter.

Assay:   None given.

Ash:    Not more than 9%.

Habitat: All sections of USA, except far west.

Description:    Asclepias occurs as entire roots, as transverse and oblique slices, or as broken fragments.  The roots are simple or rarely branched and have a few small rootlets free of cortex.  Entire roots measure up to 26 cm. in length and up to 6 cm. in diameter.  Stems are rarely present.  They are circular, smooth, and hollow, and have an easily removed cortex.  The texture is fibrous, and starchy.  The color is orange when recently gathered, but in time changes to light orange and finally gray.  The surface of the younger roots is nearly smooth, while that of the older roots is rough.  This roughness is caused by the separation of the periderm and the numerous incomplete transverse depressions, caused by the shortening of the length of the root during drying.  When the periderm is removed the surface is nearly white with darker-colored wavy lines of conducting tissue.  Transverse sections show fine concentric and coarser radiating ridges.  The fracture is very tough and