Separata encuadernada

The section Lebretonia (Pavonia, subgen. Pavonia) is defined anew by the authors. All the species included are characterized by 5 bracteoles, ovoid carpels with a prominent middle nerve and seeds with two small bunches of hair. Thre are 38 American species in this section, two in North America and the rest in South America, between the parallels 18 and 39 south. The Argentine species have been studied in detail as well as those which are systematically close to P. schrankii an P. conmutata. There 17 species in Argentina; most of them grow in the basins of the rivers Paraná and Uruguay and on the shores of the River Plate, and 5 species in the subandine and pampean "sierras" and the "sierras" of the province of Buenos Aires. Cleistogamic flowers have been observed in the following species: P. aurigloba, P. belophylla, P. consobrina, P. cryptica, P. cymbalaria, P. distinguenda. P. glutinosa, P. hastata, P. hirta, P. prionophylla, P. revoluta y P. xanthogloea. The chromosome numbers have been determined as follows: one species with 2n 28: P. mattogroensis, and 9 species with 2n 56: P. aurigloba, P. consobrina, P. cymbalaria, P. distinguenda, P. hastata, P. missionum, P. revoluta, P. rosengurttii y P. xanthogloea. The flollowing new species are described and illustrated: P. angustipetala, P. aurigloba, P. cryptica, P. kleinii, P. exserta, P. gamophylla, P. glutinosa, P. ramboi, P. reitzii, P. revoluta, P. rosengurttii and P. rubra. There is also a new combination: P. malvaceae (=Sida malvaceae Vell.).