Lou Lu

Rhaponticum uniflorum (Lou Lu, uniflower swisscentaury), formerly placed in Stemmacantha, is a perennial herb in the Asteraceae family, growing 30 to 80 centimeters tall from a stout, dark brown to blackish, often twisted woody root that constitutes the medicinal material. The stems are erect, simple, unbranched, and densely white-tomentose, especially in the upper portion. Basal leaves are large, oblong-elliptic, 10 to 30 centimeters long, deeply pinnatifid to pinnatisect with lobed segments, gray-green and softly woolly beneath; stem leaves diminish upward. Each stem terminates in a single large solitary capitulum 4 to 6 centimeters across, the involucre bowl-shaped with overlapping bracts bearing dry, scarious, brown to blackish appendages; the tubular florets are rosy purple to violet. Native to the steppes and dry montane slopes of northern China, Mongolia, Korea, and southern Siberia. The roots are harvested in spring or autumn, washed, sliced, and dried for use in formulas for heat-toxin sores and breast abscess.