Recent debates on the number of plant species in the vast lowland rain forests of the Amazon have been based largely on model estimates, neglecting published checklists based on verified voucher data. Here we collate taxonomically verified checklists to present a list of seed plant species from lowland Amazon rain forests. Our list comprises 14,003 species, of which 6,727 are trees. These figures are similar to estimates derived from nonparametric ecological models, but they contrast strongly with predictions of much higher tree diversity derived from parametric models. Based on the known proportion of tree species in neotropical lowland rain forest communities as measured in complete plot censuses, and on overall estimates of seed plant diversity in Brazil and in the neotropics in general, it is more likely that tree diversity in the Amazon is closer to the lower estimates derived from nonparametric models. Much remains unknown about Amazonian plant diversity, but this taxonomically verified dataset provides a valid starting point for macroecological and evolutionary studies aimed at understanding the origin, evolution, and ecology of the exceptional biodiversity of Amazonian forests.Amazonia | floristics | rain forests | seed plants | species diversity

Many angiosperm families are distributed pantropically, yet for any given continent little is known about which lineages are ancient residents or recent arrivals. Here we use a comprehensive sampling of the pantropical sister pair Anacardiaceae and Burseraceae to assess the relative importance of continental vicariance, long-distance dispersal and niche-conservatism in generating its distinctive pattern of diversity over time. Each family has approximately the same number of species and identical stem age, yet Anacardiaceae display a broader range of fruit morphologies and dispersal strategies and include species that can withstand freezing temperatures, whereas Burseraceae do not. We found that nuclear and chloroplast data yielded a highly supported phylogenetic reconstruction that supports current taxonomic concepts and time-calibrated biogeographic reconstructions that are broadly congruent with the fossil record. We conclude that the most recent common ancestor of these families was widespread and likely distributed in the Northern Hemisphere during the Cretaceous and that vicariance between Eastern and Western Hemispheres coincided with the initial divergence of the families. The tempo of diversification of the families is strikingly different. Anacardiaceae steadily accumulated lineages starting in the Late Cretaceous–Paleocene while the majority of Burseraceae diversification occurred in the Miocene. Multiple dispersal- and vicariance-based intercontinental colonization events are inferred for both families throughout the past 100 million years. However, Anacardiaceae have shifted climatic niches frequently during this time, while Burseraceae have experienced very few shifts between dry and wet climates and only in the tropics. Thus, we conclude that both Anacardiaceae and Burseraceae move easily but that Anacardiaceae have adapted more often, either due to more varied selective pressures or greater intrinsic lability.

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Campo rupestre Conclusions Folk classifications Local classifications, reflecting cultural perceptions of the surroundings, may be based on physiognomy or topography/drainage; a sort of folk Braun-Blanquet plant-sociology system is applied to some formations in which a species or set of confamilials is dominant. The "varillales" (from the word for "pole") on white sand in Peruvian Amazonia are characterized by the densely packed slender trees implicated by the name. "Caatinga" is derived from the Tupi for "white forest," referring to the blanched trunks so common in arid northeastern Brazil. "Mata de cipó," or liana forest, is self-explanatory. The various popular terms for formations in the Cerrado, (e.g., "campo limpo," "campo cerrado," "cerradão") describe the relative density of woody plant cover. Local names for humid forest formations tend to be oriented toward terrain, as are many of those in the scientific literature. Such terms as "várzea," "baixio" ("bajio" in Spanish), "terraço (alto and baixo)," and "barranco" involve the elevation of the terrain relative to river levels and to flooding regimes. Popular names referring to particular taxa when those taxa are locally dominant in some way. In Peruvian Amazonia, the "irapayales," relatively tall forests on sandy soils whose understory is dominated by the palm Lepidocaryum tenue (see Whitney and Alvarez 1998), and "moenales," forests on young terraces dominated by several Lauraceae. In southwestern Brazilian Amazonia and contiguous Peru, the "tabocais" or "pacales" are forests dominated by arborescent bamboos in the genus Guadua. The "wallaba" forests of Guyana are dominated by Eperua spp. This phenomenon is more frequent in drier formations, where dominance by one or a few taxa is more common. The "quebrachales" of the Chaco are dominated by Schinopsis spp. or Aspidosperma quebracho-blanco. Also in the Chaco, "palo-santales" are dominated by Bulnesia sarmientoi, and "algarrobales" are dominated by Prosopis spp. Some terms are not used consistently, or the same term may have different meanings among regions. The "caatinga" of northeastern Brazil has nothing to do with the Amazonian caatingas of the upper Rio Negro described below except perhaps the sun-bleached barks of some of their trees. "Igapó" as used by Prance (e.g., 1979) applies to forests seasonally inundated by black-water rivers, whereas most Brazilian botanists (e.g., Pires, 1973) have used the term to describe permanently flooded forests. Structure of moist forests Lowland humid tropical forests can be characterized by a disparate set of factors. The canopy is generally high (to 40 m) but often discontinuous, and emergent trees may reach 65 m in height. It is usually not possible to distinguish strata. Palms and lianas occur in varying densities. Cauliflory and buttresses are common. Compared to dry or lower montane forests, the lowland humid forests have greater stand height, height to the first branch, trunk volume, buttress height, and buttress area (see Table 295 in Holdridge 1971). Many t...

As part of an ongoing study of Anacardiaceae subfamily Spondioideae, the ten native and one introduced species of Spondias in the Neotropics are revised. The genus is circumscribed. Three new species, S. admirabilis, S. expeditionaria, and S. globosa, are described and illustrated; a key to the taxa found in the Neotropics and distribution maps are provided. The Paleotropical species and allied genera are reviewed. Diagnostic character sets include leaf architecture, habit, flower morphology, and gross fruit morphology. Notes on the ecology and economic botany of the species are provided.