Xanthorhiza simplicissima (yellowroot) is the only member of the genus Xanthorhiza, and one of very few genera in the family Ranunculaceae with a woody stem (the other notable example being Clematis). It is native to the eastern United States from Maine south to northern Florida and west to Ohio and eastern Texas. It contains the alkaloid berberine, which has a number of traditional and contemporary uses for dyeing and medicine.

The genus name as well as the common name refer to the plant's yellow roots (xantho- meaning "yellow" and rhiza meaning "root"), which was used to produce a yellow dye by Native Americans. The specific epithet refers to the simple (not branched) stems.

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