5. Acalypha rhomboidea Raf. (three-seeded mercury, rhombic
A. virginica L. var. rhomboidea (Raf.)
Map 1653, Pl.
15–60 cm long, glabrous or moderately to densely pubescent (sometimes
in vertical lines) with short, strongly curved hairs, occasionally with a few
longer, straight hairs toward the base. Leaves long-petiolate, the petiole
slightly shorter than to slightly longer than the blade, much longer than the
inflorescence bracts. Leaf blades 1–10 cm long, broadly lanceolate to
ovate or rhombic, angled to broadly angled at the base, tapered to a sharply
pointed tip, the margins with several (mostly 8–12 on each side) often
relatively closely spaced, usually blunt teeth, relatively thin-textured, the
surfaces sparsely pubescent with relatively straight, more or less appressed
hairs. Inflorescences entirely axillary spikes, 1–3 per node, each with
1–3 basal pistillate flowers below few to several nodes of staminate
flower clusters, the tip of the spike not or only slightly extending beyond the
bract. Inflorescence bracts 4.5–25.0 mm long, appearing more or less
folded longitudinally around the inflorescence, with
(5–)7–9(–11) narrowly lanceolate to oblong-lanceolate
lobes, the margins sparsely to moderately hairy, often some of the hairs
gland-tipped, the outer surface glabrous or sparsely hairy, sometimes some of
the hairs gland-tipped, lacking minute, sessile, reddish glands. Fruits
1.5–2.3 mm long, 3-locular, usually 3-seeded (rarely 1 of the ovules
aborting), the surface moderately to densely hairy, lacking tubercles or
slender projections at maturity. Seeds 1.3–2.0 mm long.
throughout the state (eastern U.S. west to North Dakota and Texas; Canada). Banks of streams and rivers, margins of ponds and lakes, bottomland forests, mesic
upland forests, and moist depressions of upland prairies; also crop fields,
fallow fields, old fields, railroads, roadsides, and disturbed areas.
(1984) pointed out problems in distinguishing A. rhomboidea from A.
virginica and treated it as a variety of that species. However, based on
his quantitative morphological studies, Levin (1999a) disagreed, noting that
not all of the traditionally used qualitative features contained consistent
differences between the species but that others served to uniquely