Xanthorhiza translates to yellowroot, which is the common name for this monotypic genus of eastern USA. Strangely, there are few photographs of its root online, but the My Weeds Are Very Sorry weblog has one, along with images of plants in cultivation. The yellow root is also visible in the image of a specimen on the North Carolina State Extension’s site: Xanthorhiza simplicissima.
Another distinguishing feature of Xanthorhiza is that it is one of the few wood-forming genera within the primarily-herbaceous buttercup family (Ranunculaceae). As a group, the Ranunculaceae have many biologically-active compounds (some poisonous at very low doses, some not); it is unsurprising that yellowroot has a long history of medicinal use.
The plant in today’s photograph was grown from seed wild-collected in West Virginia. It is forming a successful colony in UBC’s Carolinian Forest Garden.