49. Aruncus Linnaeus, Opera Var. 259. 1758.
Goat’s-beard, bride’s-feathers, barbe-de-bouc [Greek arunkos, goat’s beard, alluding to showy fingerlike clusters forming feathery flowers]
T. Lawrence Mellichamp
Herbs, perennial, clump-forming, 5–15(–20) dm, herbage glabrous or sparsely to densely hairy, ˂hairs simple, straight to curved, sometimes multicellular or glandular˃; rhizomatous, ˂rhizomes thick, branching, woody; roots coarse, fibrous˃. Stems 1–5, erect, ˂stout, simple, sometimes glaucous˃. Leaves deciduous, cauline, alternate, 2–3-irregularly ternate to odd-pinnate, equivalent to 2–3 pinnate; petiole present, ˂relatively long, base 1/2 sheathing stems˃; blade broadly ovate, ˂cauline reduced in size and complexity distally˃, 15–60 cm, thick to thin, leaflets 9–45, ˂long-petiolulate˃, broadly ovate to narrowly lanceolate, margins flat, [serrate to] doubly serrate, venation pinnate. Inflorescences terminal, 500–2500-flowered, racemes forming panicles; bracts present; bracteoles present ˂hairs simple, glandular˃. Pedicels present. Flowers unisexual (plants dioecious, rarely polygamous), 3–4 mm diam.; epicalyx bractlets 0; hypanthium shallowly bowl-shaped, 0.5–1 mm, ˂nectary ring inside with simple, glandular hairs˃; sepals persistent, 5, spreading, triangular, ˂margins entire˃; petals 5, white, obovate to elliptic, ˂base cuneate˃; staminate: stamens (15–)20(–30) in 1 series (between calyx and nectar ring), longer than petals; torus minute; pistillate: nectar ring scarcely developed, stamens rudimentary, carpels 3, free, glabrous, styles terminal; ovules 2–4. Fruits follicles, 3(or 4), ˂pedicels recurving, fruits inverted, retrorse˃, ovate-elongate, 1.5–5 mm, ˂shining˃, glabrous, dehiscent along whole adaxial suture; hypanthium persistent; sepals persistent, spreading to appressed; styles persistent, ˂forming a beak˃. Seeds 2–4, elongate, ˂membranous, caudate at both ends, scalariform-reticulate, seed coat loose˃. x = 7, 9.
Species 1: North America, Eurasia; temperate regions.
SELECTED REFERENCE Mellichamp, T. L. 1976. A Comparative Study of Aruncus (Rosaceae) and Astilbe (Saxifragaceae), and the Problem of Their Relationships. Ph.D. dissertation. University of Michigan.