Xanthorhiza Marsh. (1785), Syn Zanthorhiza L'Hẻrit., in the family Ranunculaceae, consists of 1 species from eastern North America, X. simplicissima Marsh., commonly called shrub yellow root.

Description A low shrub to 80cm, with yellow wood and suckering stems forming large patches. The leaves are mainly at the top of the stem, compound, pinnate or 2-pinnate, with toothed leaflets. The flowers are small, brownish-green, hanging in spike-like racemes, with 5 sepals, soon falling, and 5 petals, small and curved into nectaries. Stamens are 5 or 10, ovaries 5–15, forming 1-seeded, light yellow pods. Pollination is presumed to be by insects.

Key Recognition Features Divided leaves on a short stem, yellow wood, and an acrid smell when crushed.

Evolution and Relationships Close in many ways to Actaea L., another Ranunculaceae with reduced flowers and compound leaves.

Ecology and Geography In woods from southern New York state to Kentucky and Florida.

Comment Sometimes grown for its attractive leaves, and in botanic gardens as one of the few shrubby members of the Ranunculaceae.

Photograph: Xanthorriza simplicissima