Acalypha

Acalypha is a genus of flowering plants in the family Euphorbiaceae. It is the sole genus of the subtribe Acalyphinae. It is one of the largest euphorb genera, with approximately 450 to 462 species. The genus name Acalypha is from the Ancient Greek ἀκαλύφη (akalúphē) ('nettle'), an alternative form of ἀκαλήφη (akalḗphē), and was inspired by the nettle-like leaves. General common names include copperleaf and three-seeded mercury. Native North American species are generally inconspicuous most of the year until the fall when their stems and foliage turn a distinctive coppery-red. The genus is distributed mainly in the tropics and subtropics, with about 60% of species native to the Americas and about 30% in Africa. The genus includes annuals or perennial herbs, shrubs, and small trees. Most are monoecious, and some are dioecious. Indumentum of simple hair or glands, rarely of stellate hair. The leaves are alternately arranged, undivided, generally petiolate, stipulate; stipels rarely present at apex of petiole or leaf base, caduceus. The blades entire or more frequently dentate or crenate, pinnately or palmately veined. There are several types of inflorescence, terminal or axillary, frequently both, unisexual or androgynous. Male inflorescences spicate, densely flowered, with several flowers at each node subtended by a minute bract. Female inflorescences generally spicate, sometimes racemose or panicle-shaped, with 1–3(–5) flowers at each node, usually subtended by a large bract, increasing and foliaceous in the fruit, generally dentate or lobed; sometimes subtended by a small bract, entire or lobed, non accrescent in the fruit. Androgynous inflorescences usually with female flowers at proximal nodes and male flower at distal nodes. Flowers unisexual, apetalous, disc absent. Male flowers very small, shortly pedicellate, globose in bud; calyx parted into 4 small valvate sepals; stamens 4–8(–16) on a slightly raised receptacle, filaments free or basally connated; anthers with divaricate or pendulous thecae, unilocular, more or less elongated and later becoming vermiform; pollen grains oblate-spheroidal, with 3–5 pseudopores, tectate, psilate; pistillode absent. Female flowers generally sessile or subsessile, pedicellate in a few species; calyx of 3– (4–5) small sepals imbricate, connate at base; ovary of 3 carpels, surface often muricate, pubescent or papillose; ovules solitary in each cell, anatropes; styles reddish, free or basally connate, several times divided into filiform segment, rarely bifid or entire; staminodes absent.Fruits capsular, small, 3-lobed, soon dehiscing septicidally into 3 bivalved cocci; generally surrounded by the accrescent female bract. Seeds small, ovoid or ellipsoid, usually carunculate, smooth or foveolate; endosperm present, whitish; the embryo straight; cotyledons broad and flat. Allomorphic female flowers present in some species, generally terminal (sometimes median or basal) in the inflorescences; ebracteate, long pedicellate or subsessile; calyx as in the normal female flowers; ovary and fruits 1-2 locular. The genus Acalypha was described in the Species Plantarum by Linné (1753), as belonging to the monoecia monadelphia class along with other Euphorbiaceae genera such as Croton, Jatropha and Ricinus. Previously it was also included in the Corollarium Generum Plantarum (Linné, 1737). Its definition has been changed very little ever since, and it is confirmed as a natural and well specified genus. In its Species Plantarum, Linné sets forth the first three binominal names, i.e. A. virginica from North America, and A. indica and A. australis from Asia; in 1760 he describes a fourth species: A. virgata from Jamaica. In the same year, Nikolaus Joseph von Jacquin, as a result from his journey to Caribbean Sea, writes Enumeratio Systematica Plantarum, in which species A. villosa and A. carthagenensis from Colombia, and A. corensis from Venezuela are described. The first Acalypha iconographies are also shown in the books by Jacquin; there coloured sheets of A. villosa (Jacquin, 1776), A. alopecuroides (Jacquin, 1792), A. cuspidata, A. diversifolia and A. macrostachya (Jacquin, 1797) can be found. Until the late 18th century the outstanding incorporations to the genus were those from Pehr Forsskål, a Linné student, who sets forth six new species in his Flora Aegyptiaco-Arabica in 1775; and also those from Swedish botanist Olof Swartz, author of Nova Genera et Species Plantarum seu Prodromus, in 1788, where eight new species are published as a result of a journey around Western Indies. In 1789 Antoine de Jussieu also incorporates Acalypha in his Genera Plantarum. 19th century going on, Antonio José Cavanilles describes six species from Mexico: these were collected by Luis Née, a botanist from Malaspina Expedition (Cavanilles, 1800). One year later, such species are again included in his book Icones et Descriptiones Plantarum together with some excellent monochrome drawings. In 1804 and 1816, Jean Louis Marie Poiret makes the first compilation of all Acalypha known species in the Encyclopédie Méthodique, Botanique by Jean Baptiste Lamark(vol. VI and suppl. IV). There he describes forty species, thirteen of them for the first time. In 1805, Carl Ludwig Willdenow compiles and describes thirty nine Acalypha species in his Species Plantarum, in which the first classification of genus is made. The species are grouped as to whether they are monoecious or dioecious, and to the position of flowers and inflorescences. As an offspring from the American journey made by Alexander von Humboldt and Aimé Bonpland, twelve new Acalypha species, from Mexico and Colombia, are described by Sigmund Kunth in Nova Genera et Species Plantarum (1817, 1825). In 1826, Kurt Sprengel compiles fifty eighth Acalypha species in his Systema Vegetabilium, seven of them brand new. He puts them together under a key with characters similar to those used by Willdenow, finally, the herbaceous species are separated from the woody species. During the first half of the 19th century, many new species are published all around the world, with emphasis on the works by Eduard Poeppig (1841) and George Bentham (1839, 1844) about American species. In the French botanist Henri Baillon publication Étude générale du groupe des Euphorbiacées (1858), a large morphological description of genus is made, and a peculiar classification is presented: two sections are considered –“Sect. A” and “Sect. B”– depending on whether the inflorescence axis is simple or branched out, and the female flowers calyx consists of three or five sepals. Baillon continued to publish a series of works under the title Euphorbiacées américaines, to be issued in the first volumes of Adansonia journal, between 1860 and 1864. More than fifty new species of Acalypha are described thereto, most of them from South America, and specially from Brazil.