6. Acalypha virginica L. (Virginia copperleaf)
Map 1654, Pl.
15–60 cm long, sparsely to densely pubescent (sometimes in vertical
lines) with short, strongly curved hairs, usually also with sparse to dense,
longer, straight hairs. Leaves relatively short-petiolate, the petiole
1/4–1/2 as long as the blade, usually longer than the inflorescence
bracts. Leaf blades 1–12 cm long, lanceolate to narrowly ovate or
narrowly rhombic, angled or slightly rounded at the base, angled or tapered to
a sharply pointed tip, the margins with few to several (mostly 3–8 on
each side) usually broadly spaced, blunt, shallow teeth, sometimes appearing
shallowly scalloped or slightly undulate, relatively thin-textured, the
surfaces sparsely pubescent mostly along the veins with short, straight to
curved, 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 often
extending somewhat beyond the bract. Inflorescence bracts 4.5–20.0 mm
long, appearing more or less folded longitudinally around the inflorescence,
with (9–)10–15 triangular-ovate to broadly oblong lobes, the
margins sparsely to densely bristly-hairy, usually lacking gland-tipped hairs,
the outer surface sparsely hairy, usually lacking gland-tipped hairs, rarely
with sparse, 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, occasionally
with a few minute, low, warty projections when young but smooth at maturity. Seeds
1.3–2.0 mm long. 2n=40. July–October.
throughout the state (eastern U.S. west to South Dakota and Texas; introduced
in Europe). Bottomland forests, mesic to dry upland forests, savannas, upland
prairies, margins of ponds, lakes, and sinkhole ponds, and ledges and tops of
bluffs; also fallow fields, old fields, pastures, cemeteries, ditches, gardens,
railroads, roadsides, and open, disturbed areas.
(1984) pointed out problems in distinguishing A. rhomboidea, and A.
virginica, treating these taxa as varieties of A. virginica.
However, Levin (1999a) had no trouble in distinguishing them in his
quantitative morphological studies of the group. Steyermark (1963), who
suggested that A. virginica apparently was expanding its range northward
during the decades of his research on the flora, also suggested occasional
hybridization between A. virginica and A. gracilens. However,
there has been no subsequent experimental confirmation of such hybrids.
Steyermark also noted the existence of occasional specimens difficult to place
in either A. rhomboidea or A. virginica. Such
specimensfor example, occasional plants with exceptionally short
petioleswill continue to vex Missouri botanists but fortunately are
relatively rarely encountered. Although a great deal has been written about the
morphology of the complex, it would benefit from additional biosystematic and
population-genetic investigations. Even the chromosome numbers in the complex
are not known with certainty, as Millers (1964) counts based on x=10
contradict earlier reports based on x=7 (Webster, 1967).
Burrows and Tyrl
(2001) noted that, of all the temperate North American species of Acalypha,
A. virginica was the one most likely to cause problems with livestock.
Plants in the genus contain diterpene esters that can act as irritants for soft
tissues, mucous membranes, and the digestive tract.