RESUMO -Considerando que a estrutura vegetativa de espécies dos gêneros brasileiros da subtribo Laeliinae é pouco conhecida, este trabalho objetivou descrever os órgãos vegetativos de Cattleya violacea. Secções à mão livre, dos órgãos vegetativos, foram processadas segundo as técnicas usuais para anatomia vegetal. O pseudobulbo e a folha apresentam hipoderme esclerifi cada e cutícula espessa. Tais características são adaptações ao epifi tismo e à necessidade de acúmulo de água. A uniformidade das características anatômicas suporta os resultados morfoanatômicos e moleculares para a subtribo Laeliinae (tribo Epidendreae). Caracteres anatômicos e histoquímicos analisados, tais como velame não distinto em epivelame e endovelame e a presença de cristais fl avonoídicos, apresentam uniformidade genérica, o que pode servir como ferramenta para a delimitação de representantes da subtribo.Palavras-chave: adaptação, epífi tas, Laeliinae, orquídea, sistemática ABSTRACT -Anatomy of vegetative organs of Cattleya violacea (Kunth) Rolfe (Orchidaceae).Considering that the vegetative structure of species of the Brazilian genus of Laeliinae subtribe is poorly known, the vegetative organs of Cattleya violacea are described here. Freehand sections of vegetative organs were obtained according to the usual techniques for plant anatomy. Pseudobulb and leaf present sclerifi ed hypoderm and thick cuticle. Such features are adaptations to epiphytism and the necessity for water storage. Uniformity of anatomic features supports the morphoanatomic and molecular data for the subtribe Laeliinae (Epidendreae tribe). Anatomic and histochemical characters analyzed, such as undistinguished epivelame and endovelame and the presence of fl avonoid crystals, present generic uniformity, which can serve as a tool for the delimitation of the subtribe representatives.

<div class="page" title="Page 1"><div class="layoutArea"><div class="column"><p><span>To elucidate the factors which control the flower phenotypic plasticity of </span><span>Catasetum fimbriatum</span><span>, </span><span>studies focusing the floral development of the species were performed. The treatments were: high light intensity (1613 μmol.m</span><span>-2</span><span>.s</span><span>-1</span><span>); low light intensity (454 μmol.m</span><span>-2</span><span>.s</span><span>-1</span><span>) and mean light intensity (827 μmol.m</span><span>-2</span><span>.s</span><span>-1</span><span>). The floral </span><span>morphology and anatomy were analyzed to evaluate of the sequence of tissue development involved in the sexual differentiation. We found the presence of cell cluster with meristematic features in the ovaries and gynostemium </span><span>of the male and female diclinous flowers. These are responsible for the definition of the sexual expression of the </span><span>species, in the dependence of the environmental stimulus, related to the endogenous concentration of ethylene, allowing, consequently, the dedifferentiation and re-differentiation of those clusters in the sexual determination </span><span>of the flowers. There were no anatomical differences in floral tissues in different treatments. </span></p></div></div></div>