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Boa Vista Roraima, Brazil

Cavalcante C.O.,Federal University of Roraima | Flores A.S.,Institute Amparo a Ciencia | Barbosa R.I.,National Institute of Amazonian Research
Acta Amazonica | Year: 2014

Edaphic factors have been indicated as a determinant of the distribution of plant communities in Amazonia. The aim of this study was to detect which edaphic factors determine the occurrence of herbaceous legumes in Amazonian savannas. Therefore, an inventory of herbaceous flora of the family Leguminosae was conducted in 34 permanent plots established in two savanna areas of Roraima, northern Brazilian Amazon. The importance value index was higher for Chamaecrista desvauxii (24.9%), Aeschynomene hystrix (15.7%) and Galactia jussiaeana (10.8%), all having high abundance and wide distribution. The results indicated low density or absence of individuals and species in plots established on poorly drained soils (hydromorphic). Diversity and species richness tended to be higher in habitats formed on well drained soils, greater fertility and lower concentrations of exchangeable aluminum. It is suggested that poor and seasonally flooded soils tend to reduce the chances of occurrence of herbaceous legumes in savanna areas of Roraima, adversely affecting its richness/diversity.

Flores A.S.,Institute Amparo a Ciencia | Rockinger A.,Ludwig Maximilians University of Munich | Rodrigues R.S.,Federal University of Roraima | Tozzi A.M.G.A.,University of Campinas
Phytotaxa | Year: 2016

As part of a revision of the species of Crotalaria L. (Papilionoideae, Crotalarieae) occurring in Brazil, eleven lectotypifications are proposed for: Crotalaria acutiflora Benth., Crotalaria depauperata Mart. ex Benth., Crotalaria holosericea Nees & Mart., Crotalaria holosericea var. grisea Benth., Crotalaria laeta Mart. ex Benth., Crotalaria leptophylla Benth., Crotalaria rufipila Benth., Crotalaria unifoliolata Benth., Crotalaria vitellina Ker-Gawl., Crotalaria vitellina var. glabrata Benth., and Crotalaria vitellina var. minor Benth. Four new synonyms are also proposed. © 2016 Magnolia Press.

Rodrigues R.S.,Federal University of Roraima | Feitoza G.V.,Institute Amparo a Ciencia | Flores A.S.,Institute Amparo a Ciencia
Acta Amazonica | Year: 2014

We carried out a comparative morphological study to evaluate the taxonomic value of seed and seedling traits of Entada polystachya and E. simplicata (Leguminosae, Mimosoideae, Mimoseae). Seeds of both species were collected from wild populations in Roraima State, Brazil. Our results show consistent quantitative and qualitative differences between these species regarding their seeds and seedlings. Testa fracture lines, funiculus impression, lens characters, radicle shape and length, and cotyledon lobes length, seedling morphology group, number of pinnae at first node, and hypocotyl length permit a straightforward distinction of E. polystachya from E. simplicata, supporting a recent treatment of the latter taxon as a distinct species, endemic to Roraima State, northern Amazonia, Brazil.

Da Silva De Medeiros E.C.,Institute Amparo a Ciencia | Flores A.S.,Institute Amparo a Ciencia
Rodriguesia | Year: 2014

Stylosanthes is a member of the Pterocarpus clade, tribe Dalbergiae. It has 50 species with pantropical distribution and is greatly diversified in Brazilian savannas. Here we present a taxonomic study of Stylosanthes in Roraima state. Field work and herbarium surveys were extensive. Seven species were widely distributed over all savanna physiognomies: S. capitata, S. angustifolia, S. gracilis, S. viscosa, S. humilis, S. guianensis and S. scabra. An identification key, descriptions, illustrations, information on geographic distribution, habitat and uses for the species are also provided.

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