Description

This herbaceous perennial wildflower is 3-6' tall and unbranched or sparingly so. The central stem is green, stout, and terete, bluntly angular, or ribbed; it is sparsely short-pubescent along the upper half of its length, becoming glabrous below. Alternate compound leaves occur along the entire length of the stem that are evenly pinnate with 6-10 pairs of leaflets. Individual leaflets are 1¼-2½' long and ½-1' across; they are oblong-elliptic in shape and smooth along their margins. The upper leaflet surface is medium green or bluish green and hairless, while the lower surface is pale green or bluish green, often glaucous, and hairless. At the base of each leaflet, there is a short petiolule (basal stalklet) 1/8' long or less. The petioles of compound leaves are 2-6' long, light green, grooved along their upper surfaces, and either sparsely short-pubescent or hairless. At the base of each petiole, there is a pair of small stipules that are linear-lanceolate in shape and tardily deciduous. Along the upper side of each petiole near its base, there is a small gland that functions as an extra-floral nectary; this gland is often dome-shaped and dark gray-purple, with or without a short stalk at its base. The crushed foliage has an unpleasant scent. Both terminal and axillary inflorescences are produced. The terminal inflorescence is ½-1' long, consisting of either a raceme or panicle of flowers. The axillary inflorescences are up to ½' long, consisting of racemes of flowers. Individual flowers are about ¾' across, consisting of 5 spreading yellow petals, 5 spreading greenish yellow sepals, 10 stamens with dark brown anthers, and a pistil with a style that curls upward at its tip. The sepals are smaller than the petals; the former are joined together at the base and obovate in shape. The stamens are organized into three groups