Plant: annual herb; to 70 cm tall; stems erect, branched, with short recurved hairs and stalked glands, especially toward the apex Leaves: ovate, 3-8 cm long, 1.5-5 cm wide, sparsely pilose; apex acute to short attenuate; base cordate or rounded; margin serrate; almost as long as the blade, petioles with pubescence like the stems INFLORESCENCE: SPIKES of two kinds: staminate spikes axillary, 5-35 mm long on pedicels 5-15 mm long; pistillate spikes terminal (sometimes on short lateral branches and so appearing axillary), 3-7 cm long, fairly open, especially in fruit; bracts subtending pistillate flowers 3-6 mm long, with (9-)13-17 narrow lobes about 2/3 the length of the bract, densely glandular with both sessile and stalked glands Flowers: ALLOMORPHIC FLOWERS sessile; ovary obovoid, pubescent, with two irregular flanges near the apex Fruit: capsules, ca. 2 mm long, ca. 4 mm wide, sparsely short hispid and with fleshy green glandular outgrowths especially toward the apex. SEEDS 1.6-2 mm long, brown, with low bumpy ridges Misc: Moist areas, often weedy; 1000-1650 m (3200-5500 ft); Aug-Oct REFERENCES: Levin, Geoffrey A. Euphorbiaceae. Part 1. Acalypha and Cnidoscolus. J. Ariz. - Nev. Acad. Sci. 29(1): 18.
From Flora of Indiana (1940) by Charles C. Deam
Most of our specimens are from truck gardens, cornfields, and fallow fields along or near the Ohio River and near New Harmony. I have never seen it in any other habitat. In recent years it has been introduced farther north in the state. It is usually a common weed where it is found. This species seems to be adventive. It was first reported from Indiana in 1917 and none of the early botanists had seen it. Riddell (1835) says his specimen came from a hill opposite Cincinnati. Short in his Catalogue of Kentucky Plants and his four supplements does not list it. These were published between 1833-1840. Lapham reports it from Illinois between 1836 and 1857.
Duration: Annual Nativity: Native Lifeform: Forb/Herb General: Erect, simple to ascending branched annual 10-80 cm tall with dark green minutely puberulent to glabrate stems and foliage. Leaves: Slender petioles 1-7 cm long, blades ovate 2-6 cm wide, 2.5-12 cm long, obtuse, rounded, sometimes subcordate at base, acute to short-acuminate at apex, serrate, thin, becoming sparsely puberulent to nearly glabrous and puncticulate in age. Flowers: Slender axillary staminate spikes 1-3 cm long, flowers separate below, densely crowded above middle; pistillate spikes terminal on branches 2-7 cm long, bracts 5-9 mm in diameter, lobed one-half to two-thirds of way to base into 11-15 narrowly subulate-linear lobes, these closely beset with short-stiped, nearly granular glands. Fruits: Depressed-globose capsule 3.5-4.5 mm wide, 2-3 mm high, strongly 3-lobed, papillose and muricate on upper surface. Ecology: Found along washes, in shade of shrubs and in wet cienegas; 3,000-5,500 ft (914-1676 m); flowers June-October. Distribution: Most of eastern US, from AZ north to NE east to NJ; south to s MEX and in S. Amer. Notes: Distinguished as being dark-green erect annuals with finely dentate, ovate leaves; dense inflorescence spikes with densely-stacked flowers which are subtended by leaf-like bracts; the comb-like teeth on bracts below female (pistillate) flowers help to tell this species apart. Ethnobotany: Unknown Etymology: Acalypha is from Greek akalephes for nettle, while ostryifolia might mean having leaves like the genus Ostrya. Synonyms: Acalypha caroliniana Editor: SBuckley 2010, FSCoburn 2015
Erect, 3-6 dm, branched above, finely hairy; lvs widely spreading or often drooping, thin, ovate-oblong to broadly ovate, abruptly short-acuminate, finely and regularly toothed, rounded to cordate at base; pistillate fls in terminal spikes 3-8 cm, also a few in the axillary staminate clusters; bracts tending to embrace the fr, cleft to about the middle into 13-17 linear segments; fr deeply 3-lobed, 3-4 mm thick, beset with slender projections and also ±pubescent. A weed in grain-fields, gardens, and waste places; N.J. to Ind. and Neb., s. to Fla. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.