2. Acalypha gracilens A. Gray (slender three-seeded mercury)

A. gracilens var. delzii Lill. W. Mill.

A. gracilens var. fraseri (Müll. Arg.) Weath.

Map 1650

Stems 10–60 cm long, moderately to densely pubescent with short, strongly curved hairs. Leaves short-petiolate, the petiole 1/16–1/4 as long as the blade, shorter than to occasionally about as long as the inflorescence bracts. Leaf blades 1–7 cm long, narrowly lanceolate to more commonly oblong-lanceolate, oblong, or narrowly ovate, angled or slightly rounded at the base, angled or tapered to a usually sharply pointed tip, the margins nearly entire or more commonly with few to several (mostly 3–12 on each side) usually broadly spaced, blunt, minute teeth, often appearing shallowly scalloped, relatively thin-textured or somewhat thicker and stiffer, the surfaces sparsely to densely pubescent with short, straight to curved, loosely appressed hairs. Inflorescences entirely axillary spikes, 1–3 per node, each with 1–3 basal pistillate nodes (each with a separate folded bract) below several nodes of staminate flower clusters, the tip of the spike extending well beyond the bracts. Inflorescence bracts 1 per pistillate node, 4–25 mm long, appearing more or less folded longitudinally around the inflorescence, with (9–)10–17 linear to lanceolate or narrowly oblong lobes, the margins sparsely to moderately bristly-hairy, at least some of the hairs usually gland-tipped, the outer surface sparsely to densely hairy, usually at least some of the hairs gland-tipped, usually also with sparse to moderate minute, reddish, sessile glands. Fruits 1.5–2.3 mm long, 3-locular, usually 3-seeded (rarely 1 of the ovules aborting), the surface moderately hairy and sometimes also with minute, sessile glands, lacking tubercles or slender projections at maturity. Seeds 1.2–2.0 mm long. June–October.

Uncommon in eastern Missouri and disjunctly in a few southwestern counties (eastern U.S. west to Iowa and Texas). Banks of streams and rivers, margins of ponds and lakes, savannas, glades, and sand prairies; also ditches, gardens, roadsides, and disturbed areas.

Miller (1964) speculated that midwestern populations of A. gracilens might be relatively recent introductions to the region. However, Levin (1999b) concluded that these populations had been in the area long enough for minor morphological differences to accumulate between them and other populations from the main portion of the species range farther to the south and east. In Missouri, although the species currently is found mostly at disturbed sites, the oldest specimens date back to George Engelmanns collections from the 1840s in seemingly natural habitats along the Mississippi River near St. Louis.