Anemopaegma

Abstract: The radiation of angiosperms is associated with shifts among pollination modes that are thought to have driven the diversifi cation of flforms. However, the exact sequence of evolutionary events that led to such great diversity in fltraits is unknown for most plant groups. Here, we characterize the patterns of evolution of individual fl oral traits and overall fl oral morphologies in the tribe Bignonieae (Bignoniaceae). We identifi ed 12 discrete traits that are associated with seven fl oral types previously described for the group and used a penalized likelihood tree of the tribe to reconstruct the ancestral states of those traits at all nodes of the phylogeny of Bignonieae. In addition, evolutionary correlations among traits were conducted using a maximum likelihood approach to test whether the evolution of individual fl oral traits followed the correlated patterns of evolution expected under the “ pollination syndrome ” concept. The ancestral Bignonieae fl ower presented an Anemopaegma -type morphology, which was followed by several parallel shifts in flmorphologies. Those shifts occurred through intermediate stages resulting in mixed fl oral morphologies as well as directly from the Anemopaegma -type morphology to other fl oral types. Positive and negative evolutionary correlations among traits fi t patterns expected under the pollination syndrome perspective, suggesting that interactions between Bignonieae fl owers and pollinators likely played important roles in the diversifi cation of the group as a whole.

Abstract: Despite the general belief that the interaction between extrafloral nectaries (EFNs) and ants is mutualistic, the defensive function of EFNs has been poorly documented in South American savannas. In this article, we evaluate the potential impact of EFNs (benefits and costs) on two species of plants from the dry areas of Central Brazil, Anemopaegma album and Anemopaegma scabriusculum (Bignoniaceae). In particular, we characterize the composition of substances secreted by the EFNs, test whether EFNs attract ants, and whether ants actually present a defensive role, leading to reduced herbivory and increased plant fitness. Histochemical analyses indicated that EFNs from both species of Anemopaegma secrete an exudate that is composed of sugars, and potentially lipids and proteins. Furthermore, EFNs from both species were shown to present a significant role in ant attraction. However, contrary to common expectations, ants were not found to protect plants against herbivore attack. No effect was found between ant visitation and flower or fruit production in A. album, while the presence of ants led to a significant decrease in flower production in A. scabriusculum. These results suggest that EFNs might present a similar cost and benefit in A. album, and a higher cost than benefit in A. scabriusculum. Since the ancestor of Anemopaegma occupied humid forests and already presented EFNs that were maintained in subsequent lineages that occupied savannas, we suggest that phylogenetic inertia might explain the presence of EFNs in the species of Anemopaegma in which EFNs lack a defensive function.

Abstract: This paper presents the floristic study of the Bignoniaceae in the Serra da Canastra National Park, Southeastern of Minas Gerais State. Fiftheen species belonging to 11 genera were confirmed, being Arrabidaea, Anemopaegma and Jacaranda the most representative, with three, two and two species, respectively. Analytic keys, descriptions, illustrations, comments, geographical distribution, and flowering and fruiting of each species are presented.

Abstract: Rivera, G. L. 2000. Nuptial nectary structure of Bignoniaceae from Argentina. Darwiniana 38(3-4): 227-239. Nuptial nectary characteristics were investigated in 37 taxa of Bignoniaceae. A nuptial nectary associated to the floral axis was found in all species. Two main types can be distinguished according to their degree of development and functionality: 1) vestigial and non-secretory and 2) well-developed and secretory. The former is characteristic of Clytostoma spp., while the latter is found in the remaining species. Two subvarieties of the secretory type of nectary can be discerned according to their position and shape: 1) annular, found in Adenocalymma, Amphilophium, Anemopaegma, Arrabidaea, Dolichandra, Eccremocarpus, Macfadyena, Melloa, Pithecoctenium, Tabebuia, and Tecoma, and 2) cylindrical, found in Argylia, Cuspidaria, Jacaranda, Mansoa, Parabignonia, Pyrostegia, and Tynnanthus. Anatomically, two tissues are distinguished: 1) a single-layered epidermis covered by a cuticle and a variable number of stomata, and 2) a secretory tissue composed of compactly arranged parenchyma cells. Both nectary size and nectary/ovary ratio were usually larger in lianas (Bignonieae) than in trees (Tecomeae). Nectary type proved to be consistent among species of same genus but not among genera of same tribe. Nectary features such as vascularization, presence of trichomes and nectary type were constant within the analyzed species and therefore have a reliable taxonomic value.