ORIGINAL ARTICLE Floral ontogeny of Aeschynomene falcata and A. sensitiva (Leguminosae: Papilionoideae) supports molecular phylogenetic data Diana Salles Sampaio • Maria Cecı ´lia de Chiara Moc ¸o • Jorge Ernesto Araujo Mariath Received: 5 July 2012 / Accepted: 26 November 2012 / Published online: 21 December 2012 Ó Springer-Verlag Wien 2012 Abstract Floral ontogeny and morphology of the Legu- minosae are of interest because of their potential to provide characteristics useful for phylogeny. To determine if these features corroborate the phylogenetic segregation of the section Ochopodium from Aeschynomene, this study used comparative analysis between Aeschynomene falcata and A. sensitiva, which are within the sections Ochopodium and Aeschynomene, respectively. Flower buds were analysed by use of scanning electron microscopy. Aeschynomene falcata has a unidirectional initiation of sepals from the abaxial side, and a tendency toward whorled initiation for petals and stamens. At maturity, it has a calyx tube with five lobes, a pubescent standard petal, keel petals with coherent (but not fused) margins above and below the stamens, and a carpel with a long hairy stipe. Aeschy- nomene sensitiva has a distinct initiation pattern of petals (1st abaxial, 2nd adaxial, and 3rd lateral) and a tendency toward whorled initiation of sepals and stamens. Overlap between sepals, petals, and antesepalous stamens initiation was observed. At maturity, A. sensitiva has a glabrous bilobed calyx and a glabrous standard petal, keel petals postgenitally fused above the stamens, and a carpel with a short and glabrous stipe. Floral ontogeny and morphology of A. falcata are very similar to those of Machaerium and Dalbergia species so far studied, corroborating the phylo- genetic proximity of section Ochopodium to these genera. Important features of the floral ontogeny of A. sensitiva seem to be related to the origin of the bilobed calyx, which is shared with the rest of Aeschynomeninae except section Ochopodium, suggesting they are synapomorphies for those species. Keywords Aeschynomeninae  Dalbergia  Dalbergioid legumes  Floral morphology  Machaerium  Section Ochopodium Introduction Phylogenetic relationships between the tropical tribes Aeschynomeneae, Adesmieae, Dalbergieae (except for some genera), and Desmodieae (only Bryinae) have been verified, as has the existence of a dalbergioid clade that comprises the subclades Adesmia, Pterocarpus, and Dal- bergia, each consisting of several genera (Lavin et al. 2001; Wojciechowski et al. 2004; Klitgaard and Lavin 2005). Aeschynomeneae, consisting of five subtribes, is distrib- uted within these three subclades (Lavin et al. 2001; Klitgaard and Lavin 2005), corroborating other studies revealing the status of the tribe as an artificial group (Chappill 1995; Doyle et al. 1997). The eight genera of Aeschynomeninae, which include Aeschynomene, form part of the Dalbergia subclade, together with 14 genera that are within other subtribes of Aeschynomeneae, and Dalbergia and Machaerium of Dalbergieae (Lavin et al. 2001; Klitgaard and Lavin 2005). Aeschynomene consists of the sections Ochopodium, including species with basifixed stipules, and Aeschynomene, D. S. Sampaio (&) Campus Umuarama, Instituto de Biologia, Universidade Federal de Uberla ˆndia, Bloco 2D, Programa de Po ´s-Graduac ¸a ˜o em Biologia Vegetal, Umuarama, Uberla ˆndia, MG 38400-902, Brazil e-mail: sampaiodsbot@yahoo.com.br M. C. de Chiara Moc ¸o  J. E. A. Mariath Instituto de Biocie ˆncias, Departamento de Bota ˆnica, Universidade Federal do Rio Grande do Sul, Av. Bento Gonc ¸alves 9500, Bloco 4, Pre ´dio 43423, Agronomia, Porto Alegre, RS 91501-970, Brazil 123 Plant Syst Evol (2013) 299:499–513 DOI 10.1007/s00606-012-0739-9