Flora of North America species comparison

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Acalypha arvensis

Acalypha monococca

field copperleaf

oneseed Mercury, slender threeseed Mercury
Habit Herbs, annual, 2–8 dm, monoecious. Herbs, annual, 1–4 dm, monoecious.
Stems

erect to ascending, short-pubescent and densely [sparsely] hirsute.

erect, pubescent.
Leaves

petiole 0.5–4 cm, not stipitate-glandular;

blade rhombic-ovate to rhombic-lanceolate, 2–9(–12) × 1.2–5(–6.5) cm, base cuneate to rounded, margins serrate, apex obtuse to acute.

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

unisexual or bisexual, axillary;

staminate peduncle 0.3–2.5 cm, not stipitate-glandular, fertile portion 1.5–3[–6] cm;

pistillate peduncle 0.4–3 cm, not stipitate-glandular, fertile portion 2.5–4[–8] × 1–2 cm;

bisexual similar to pistillate, with staminate portion 0.4–0.7 cm;

allomorphic pistillate flowers common, terminal on pistillate and bisexual 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.
Pedicels

of allomorphic flowers rudimentary if borne above staminate flowers or 10–18 mm if borne above normal pistillate flowers.

Pistillate flowers

pistil 3-carpellate (normal flowers), (1–)2-carpellate (allomorphic flowers);

styles multifid or laciniate.

pistil 1-carpellate;

styles multifid or laciniate.
Capsules

smooth, hispidulous;

allomorphic fruits ovoid, 1.5–1.6 × 1.2–1.3 mm, muricate, sparsely to densely puberulent.

smooth, pubescent.
Seeds

1.1–1.5 mm, minutely pitted.

1.6–2.4 mm, shallowly pitted.
Pistillate

bracts (normal flowers) very densely crowded (inflorescence axis not visible between bracts), 6–12 × 4–6 mm, abaxial surface long-hirsute (hairs to 2 mm) and stipitate-glandular;

lobes 3–7, proximally deltate with linear tips, 1/2–2/3 bract length, smooth; of allomorphic flowers absent.

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.

Acalypha arvensis

Acalypha monococca
Phenology Flowering and fruiting summer–fall. Flowering and fruiting summer–fall.
Habitat Disturbed areas. Pine and oak woods, prairies, barrens, on sandy or shallow rocky soils.
Elevation 10–50 m. (0–200 ft.) 80–600 m. (300–2000 ft.)
Distribution
from FNA
FL; Mexico; Central America; West Indies; n South America; c South America [Introduced in North America]
from FNA
AR; IL; KS; KY; LA; MO; OK; TX
[WildflowerSearch map]
[BONAP county map]
Discussion

Acalypha arvensis became established in the United States in the 1980s and is now known from scattered localities throughout peninsular Florida. Some recent literature misapplies A. aristata Kunth to this species, but that name is a synonym of A. alopecuroidea.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

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.

(Discussion copyrighted by Flora of North America; reprinted with permission.)
Source FNA vol. 12, p. 167. FNA vol. 12, p. 171.
Parent taxa Euphorbiaceae > Acalypha Euphorbiaceae > Acalypha
Sibling taxa
A. alopecuroidea, A. australis, A. californica, A. chamaedrifolia, A. deamii, A. gracilens, A. monococca, A. monostachya, A. neomexicana, A. ostryifolia, A. phleoides, A. poiretii, A. radians, A. rhomboidea, A. setosa, A. virginica, A. wilkesiana
A. alopecuroidea, A. arvensis, A. australis, A. californica, A. chamaedrifolia, A. deamii, A. gracilens, A. monostachya, A. neomexicana, A. ostryifolia, A. phleoides, A. poiretii, A. radians, A. rhomboidea, A. setosa, A. virginica, A. wilkesiana
Synonyms A. gracilens var. monococca, A. gracilens subsp. monococca
Name authority Poeppig: in E. F. Poeppig and S. L. Endlicher, Nov. Gen. Sp. Pl. 3: 21. (1841) (Engelmann ex A. Gray) Lillian W. Miller & Gandhi: Sida 13: 123. (1988)
Web links 
Unless otherwise noted, all data comes from the online version of the Flora of North America, who have made most of their content available via a Creative Commons license (CC BY 4.0).



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