2. Acalypha gracilens A. Gray (slender three-seeded mercury)
A. gracilens var. delzii Lill. W. Mill.
A. gracilens var. fraseri (Müll. Arg.) Weath.
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.
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
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.
concluded, based on a detailed quantitative analysis of morphological variation
in the A. gracilens/monococca complex, that two species should be recognized,
but that recognition of varieties within A. gracilens was unwarranted.
In Missouri, A. gracilens tends to be more robust than A. monococca,
with bigger and broader leaves, as well as with longer and more strongly
exserted spikes (with more pistillate nodes and a more elongate staminate
portion with more nodes). Intergradation and possible hybridization between A.
gracilens and A. virginica is discussed further in the treatment of