Shrubs or subshrubs. Leaves entire or sometimes palmately lobed. Flowers sometimes solitary but usually grouped in cymose or racemose inflorescences. Epicalyx present of three lobes larger than calyx, lobes linear to lanceolate or ovate. Calyx with one to three costae. Corolla pink to purple, petals sometimes auriculate, apically notched. Staminal column antheriferous at apex. Fruits schizocarpic. Styles and mericarps 10-17. Mericarps smooth or hairy, 1-celled and 1seeded, dehiscent apically and ventrally. Endoglossum absent.
Malvastrum (Malvaceae): Perennial shrubs or subshrubs. Leaves ovate to lanceolate, non lobed. Flowers solitary in the leaf axils or aggregated in apical spikes or racemes. Epicalyx of 3 filiform or spatulate bracts. Calyx costae absent. Corolla yellow to orange. Styles and mericarps (5)8-18. Mericarps indehiscent, horseshoe shaped with a prominent ventral notch. Single seeded, glabrous.
Southern Brazil, northern Argentina and Uruguay. M. bullata (Ekman) Krapov., Brazil (Paraná, Rio Grande do Sul, Santa Catarina), M.catharinensis Krapov., Brazil (Paraná, Santa Catarina), M.dusenii (Ekman) Krapov., Brazil (Paraná, Rio Grande do Sul, Santa Catarina), M.glomerata (Hook.& Arn.) Krapov., Argentina, Brazil (Rio Grande do Sul, Santa Catarina), Uruguay, M.hatschbachii Krapov. Brazil (Paraná), M.leitei Monteiro. Brazil (Sao Paulo- known from type locality only), M.ptarmicifolia (A.St.-Hil. & Naudin) Krapov., Argentina, Brazil (Paraná, Rio Grande do Sul, Santa Catarina), M.reitzii Krapov., Argentina, Brazil (Santa Catarina), M.smithii Krapov., Brazil (Paraná), M. triangularifolia Krapov., Brazil (Rio Grande do Sul –known from type locality only)
Status in Neotropics (Native, Cultivated, Naturalised, Endemic): Native
Grows in low places on the banks of marshes, rivers and streams, in riparian forests. Altitude range across species 800-1900 m (Krapovickas 1951 & 2003)
Tropical and subtropical moist evergreen forests
Temperate grasslands, savannas, and shrublands
Krapovickas, during his revision of Malvastrum A.Gray, recognized a group of 5 species from South America which had a sufficient number of characters to constitute a separate genus – Monteiroa (Krapovickas, 1951).