18. Acalypha monococca (Engelmann ex A. Gray) Lillian W. Miller & Gandhi, Sida. 13: 123. 1988.
Oneseeded mercury Oneseeded mercury
Acalypha gracilens A. Gray var. monococca Engelmann ex A. Gray, Manual ed. 2, 390. 1856; A. gracilens subsp. monococca (Engelmann ex A. Gray) G. L. Webster
Herbs, annual, 1–4 dm, monoecious. Stems erect, pubescent. Leaves: petiole 0.2–1(–1.2) cm; blade linear-lanceolate to linear, 1.7–6(–7) × 0.3–1.2 cm, base cuneate, margins usually subentire, sometimes shallowly serrate, apex acute. Inflorescences bisexual, axillary; peduncle 0.1–0.6 cm, pistillate portion 0.6–1.2 × 0.8–1.5 cm or pistillate bract solitary, staminate portion 0.1–2.5 cm; allomorphic pistillate flowers absent. Pistillate bracts loosely arranged to crowded (inflorescence axis clearly to scarcely visible between bracts) or solitary, 8–13 × 11–16 mm, abaxial surface sparsely to densely pubescent, red sessile-glandular, and rarely stipitate-glandular; lobes (7–)9–13(–17), deltate, 1/10–1/4 bract length. Pistillate flowers: pistil 1-carpellate; styles multifid or laciniate. Capsules smooth, pubescent. Seeds 1.6–2.4 mm, shallowly pitted.
Flowering and fruiting summer–fall. Pine and oak woods, prairies, barrens, on sandy or shallow rocky soils; 80–600 m; Ark., Ill., Kans., Ky., La., Mo., Okla., Tex.
Even when fruits have dehisced, Acalypha monococca is easily distinguished from A. gracilens and all other species in the genus by its curved, needlelike columellae.