19. Xanthorhiza Marshall, Arbust. Amer. 167. 1785.
Yellowroot [Greek xanthos, yellow, and rhiza, root]
Bruce D. Parfitt
Shrubs , deciduous, from long, slender, yellow rhizomes. Leaves cauline, petiolate; cauline leaves alternate. Leaf blade 1-2-pinnately compound; leaflets lance-ovate to broadly ovate or rhombic, margins variously sharply cleft, incised, or serrate. Inflorescences axillary, many-flowered panicles, 5-21 cm; bracts scalelike, not forming involucre. Flowers bisexual, radially symmetric; sepals persistent in fruit, 5, dark brown-purple to greenish yellow, plane, lanceolate to oblanceolate, usually clawed, ca. 2.5-5 mm; petals 5, distinct, brown-purple, plane, peltate, 0.5-0.9 mm; nectary terminal, transversely oblong, 2-lobed; stamens 5 (or 10); filaments with base expanded; staminodes absent between stamens and pistils; pistils (2-)5-10, simple; ovules 2, basal ovule aborting; style present. Fruits follicles, aggregate, sessile, compressed, obliquely oblong or somewhat sickle-shaped, sides not veined; beak becoming abaxial, curved, 0.4-0.8 mm. Seeds reddish brown, ovoid, smooth. x =18.
Species 1 (1 in the flora): North America.