Perennial herb 1 - 2 m tall Stem: erect. Leaves: alternate, stalked, pinnately compound (divided up to three times), to 50 cm long. Inflorescence: either male or female, found on separate plants (dioecious), borne at ends of stems in narrow pyramidal spike-like clusters, 10 - 30 cm long. Flowers: white, tiny, having fused sepals with triangular lobes and petals to 1 mm long. Male flowers have more than fifteen stamens, and female flowers usually have three pistils. Fruit: a reflexed follicle, olive green, 1.5 - 2 mm long, egg-shaped, opening along one side. Leaflets: stalked, green, 5 - 15 cm long, narrow to broad egg-shaped to nearly oblong with a pointed tip and rounded to heart-shaped base, rarely two-lobed, toothed. The bases of the lateral leaflets are often unequally sided.
Similar species: Aruncus dioicus var. pubescens differs from the typical variety by having larger (1.7 - 2.5 mm long), nearly cylindrical fruits and grayish green leaves that are usually hairy underneath.
Habitat and ecology: In the Chicago Region, this species is only found in Grundy County along the Illinois River. Elsewhere in Illinois, it is found in rich woods.
Occurence in the Chicago region: native
Notes: This species is grown in shady, moist locations in the garden. Male cultivars are commonly planted as the flowers are showier than those of female plants.
Etymology: Aruncus is the classical name for goat's beard. Dioicus means dioecious, or having separate male and female plants.
Erect, 1-2 m; lvs to 5 dm; lfls lance-ovate or ovate- oblong to broadly ovate, 5-15 cm, acuminate, doubly serrate, rounded to cordate at base, the lateral usually
oblique, sometimes 2-lobed; infl 1-3 dm; pet ca 1 mm or less; fr reflexed, 2 mm, with persistent style; 2n=18. Rich, north-facing woods; Pa. to O., Ind., and Io., s. to N.C., Ala., and Ark. May, June. The poorly defined, chiefly western var. pubescens (Rydb.) Fernald has subcylindric frs, and the lvs are usually or always pubescent beneath, in contrast to the chiefly more eastern var. dioicus, with semi-ovoid frs (strongly convex on the back) and with the lvs glabrous or pubescent beneath. (A. allegheniensis)
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.