Perennial or sometimes annual shrubs or subshrubs, erect, with stellate pubescence. Leaves petiolate, usually unlobed, crenate or dentate. Inflorescence solitary in leaf axils, or aggregated into apical sikes or racemes. Epicalyx of 3 filiform or spathulate bracts. Calyx 5-lobed. Corolla yellow or orange. Staminal column filamentiferous at apex. Fruits schizocarpic. Styles and mericarps (5)8-18. Mericarps horseshoe shaped, indehiscent, with prominent ventral notch, 1 seeded. With or without a small endoglossum.
Sida: Malvastrum has 3 filiform bract s whereas Sida has no epicalyx bracts.
Sphaeralcea: Malvastrum has 1 ovule, Spaeralcea has 2 ovules.
Malva: Malvastrum has horseshoe shaped mericarps, not found in Malva.
Almost pantropical, with a distribution from North America, through the Caribbean, to Central and South America as far as Argentina and extending to Australia. Malvastrum grandiflorum Krapov. endemic to Bolivia. M. scoparioides Ulb. endemic to Peru. M. tomentosum subsp. pautense S.R.Hill endemic to Ecuador.
Status in Neotropics (Native, Cultivated, Naturalised, Endemic): Native in the neotropics, with some introduced taxa e.g. M. americanum (L.) Torr. var. americanum.
Central America (3)
French Guiana (1)
Alkaline soils preferred (M. coromandelianum (L.) Garcke). Populations often found in the vicinity of limestone outcrops. Species in Ecuador and Peru often found in unstable volcanic zones. M. americanum and M. coromandelianum are well-adapted to disturbed lowlands and river valleys.
Tropical and subtropical moist evergreen forests (Species are restricted to areas lacking prolonged exposure to temperatures below zero degrees.)
Tropical and subtropical grasslands, savannas, and shrublands (Semi arid environments, often at high altitude.)
Montane grasslands and shrublands
Mangrove (Coastal regions in South America, to North Eastern Argentina. River drainage systems from sea level to 2600m.)
Materials: Used as a broom (M. tomentosum – Peru)
Medicines: M. coromandelianum leaves used to clean wounds and also used for dysentery in Mexico. Also shown to be active against MRSA (Sittiwet et al, 2008), used for emollient poultices (due to the presence of mucilage in the leaves), and against headaches (Standley 1930).
Vernacular name: Central America: M. tomentosum: escoba cimarrona, M. americanum: olotillo. Caribbean: M. tomentosum: balai sauvage, M. coromandelianum: escoba, wild okra and wire weed, M. corchorifolium: herbe a balay. Brazil: Malva, false mallow. Ecuador: M. coromandelianum: escoba de bruja, M. americanum: malva loca, malva silvestre. Galápagos: M. coromandelianum: escoba de bruja
Many names, previously belonging to Malvastrum, have been moved to the following genera: Acaulimalva (Krapovickas 1974), Anisodontea (Bates 1969), Malacothamnus (Greene 1906), Nototriche (Hill 1906), Sphaeralcea (Krapovickas 1949), Tarasa (Krapovickas 1954) and Urocarpidium (Krapovicks 1954).