Vania Goncalves Esteves

Palynology of selected species of Fissidens (Hedw.)

Spores from 19 species of the subgenus Aloma Kindb. of the moss genus Fissidens were analyzed by light and scanning electron microscopy. Aloma is the largest subgenus of Fissidentaceae and is characterized by the presence of a peristome of scariosus type. The spores of the subgenus Aloma are present in monads, size small to very small, heteropolar, plano-convex, with a proximal aperture region, and the sporoderm is formed by a perine, exine, and intine. The intine is not stratified, the exine is psilate, and the perine granulated. The ornamentation elements may occur singly or grouped on the surface of the spore. The aperture region shows irregular contours, ranging from circular to elongated, due to the weakness of the sporoderm proximal pole. The observed variations among species are related to different patterns of distribution of the sporoderm granules and nanogranules. Quantitative analysis combined with qualitative results did not allow all species of the subgenus Aloma to be distinguished. The results of this study demonstrate that the spore is a useful tool for taxonomic studies, and suggest that its characters be included in phylogenetic analyses, to assist in the reconstruction of the evolutionary history of mosses.

Estudo polínico de nove espécies da subtribo Baccharinae Less. (Astereae-Asteraceae), ocorrentes no sul do Brasil

Sao palinologicamente estudadas cinco especies de Baccharis L. ( B. oblongifolia (Ruiz & Pavon) Pers., B. leucocephala Dusen, B. longoattenuata A.S. de Oliveira, B . glutinosa Pers. e B. riograndensis Teodoro et Vidal), tres especies de Heterothalamus Less. ( Heterothalamus alienus (Spreng.) O. Kuntze, H . psiadioides Less., H . rupestris Deble, Oliveira & Marchiori) e uma especie de Heterothalamulopsis Deble, Oliveira & Marchiori ( Heterothalamulopsis wagenitzii (F. Hellw.) Deble, Oliveira & Marchiori). As amostras foram obtidas de material herborizado e os graos de polen foram acetolisados, medidos, descritos, analisados e fotomicrografados sob microscopia de luz; para os nao acetolisados, usou-se microscopia eletronica de varredura. Os graos de polen foram caracterizados quanto a forma, as dimensoes, ao tipo da abertura, a ornamentacao da superficie e a espessura da exina. Os resultados mostram que, para os tres generos, os graos de polen sao pequenos ou medios, isopolares, oblato-esferoidais ou prolato-esferoidais, tricolporados, com endoabertura lalongada, exina espinhosa e caveada. Proprios da tribo Astereae, nao e possivel a separacao dos generos estudados, com base nos atributos palinologicos.

Pollen morphology of Carapa species (Meliaceae) from the Brazilian Amazon

The crabwood (Carapa) represents an important source of natural resources. The objective of this work was to study the pollen morphology of the three species of Carapa (Meliaceae) registered in the Brazilian Amazon. The pollen grains were obtained from floral buds, pistillate and staminate flowers of Carapa guianensis, C. surinamensis and C. vasquezii. In order to explore the taxonomic implications of the pollen study for these species of Carapa, lactic acetolysis method was used for light microscopy study. Furthermore, the non-acetolyzed material was used in the study of the scanning electron microscopy. It was found that the three Carapa species present little variations in pollen morphology. Compared to the other species this study, Carapa vasquezii has higher values for the length and width of endoaperture; however, it has lower values for polar and equatorial diameter, equatorial diameter in polar view and apocolpium side.