Lespedeza capitata Michx. (round-headed bush clover, roundhead lespedeza)

L. capitata f. argentea Fernald

L. capitata var. stenophylla Bissell & Fernald

L. capitata var. vulgaris Torr. & A. Gray

Pl. 400 i–k; Map 1768

Plants perennial herbs. Stems 50–200 cm long, 3–10 mm in diameter near the base, erect or strongly ascending, generally unbranched below the midpoint, densely pubescent with spreading or appressed hairs, often with a silvery or tawny appearance, the hairs not confined to longitudinal ridges, becoming sparsely pubescent or even glabrous toward the base. Primary median leaves with the petiole short and stout, 1–6 mm long, 0.7–1.0 mm wide, densely spreading- or appressed-hairy. Stipules 2–6 mm long, linear-triangular to nearly hairlike. Leaflets 20–45 mm long, 6–10 mm wide, the shape more variable than in other species, elliptic to oblong, rounded or rarely slightly angled at the base, rounded or rarely somewhat pointed at the tip, often with a silvery or tawny sheen, the upper surface silvery-hairy to nearly glabrous, the undersurface moderately to densely appressed-hairy. Axillary leaves not well-developed. Inflorescences primarily from the axils of upper leaves, unbranched clusters or short, dense racemes, generally equaling or shorter than the subtending leaves but sometimes exceeding them. Flowers 16–40 per raceme, the axis usually hidden by the flowers. Calyces with the tube 0.7–1.0 mm long, the lobes 6–13 mm long. Corollas 8–10 mm long, cream-colored with purple markings on the banner, the keel nearly equal to or longer than the wings. Fruits from open and cleistogamous flowers 4–5 mm long, the calyx longer than the fruit. Seeds 2.5–3.0 mm long, olive green to brown or nearly black. 2n=20. July–October.

Scattered nearly throughout the state (eastern U.S. west to South Dakota and Texas; Canada). Upland prairies, loess hill prairies, glades, savannas, sand savannas, tops of bluffs, openings of mesic to dry upland forests, banks of streams; also old fields, railroads, and roadsides.

The presumed hybrid between this species and L. hirta (L. ×longifolia DC.) has the congested inflorescences of L. capitata, but with the longer petioles and inflorescence stalks of L. hirta and leaves of intermediate shape. This hybrid was noted by Clewell (1966b) as “abundant.” The presumed hybrid between L. capitata and L. frutescens (L. ×manniana Mack. & Bush) often has the calyx and corolla lengths similar to L. capitata, but with purple corollas and inflorescences that are slightly longer than the leaves. The putative cross between L. capitata and L. virginica (L. ×simulata Mack. & Bush) often resembles an extremely narrow-leafleted form of L. capitata vegetatively except for longer and more slender petioles. Another form more closely resembles L. virginica vegetatively but has calyx lobes more similar to those of L. capitata. The corollas often are purple, but may be yellow, and often are borne in relatively diffuse racemes at the tips of axillary branches that far exceed the subtending leaves, unlike either of the presumed parents.