The genus Palicourea - Psychotrieae tribe, comprising around 200 species of shrubs and small trees, is distributed from Mexico to northeastern Argentina. This group particularly stands out for containing indol alkaloids, which are often toxic to cattle. The aim of this work was to contribute to the knowledge of the family Rubiaceae, emphasizing aspects of the leaf morpho-anatomy of Palicourea longepedunculata. The botanic material was collected in Mata do Paraíso Forest Reserve (RFMP), in Viçosa, Minas Gerais, Brazil, and the control was kept in the VIC herbarium. Fully-expanded leaves from the 4th node were fixed in FAA50 and preserved in ethanol 70%. Cross and longitudinal sections of the petiole and leaf blade were obtained by means of rotatory microtome, and permanent slides were mounted according to the usual methodology. The leaves are simple, opposite, whole, oval lanceolate, dorsiventral and hypostomatic. The petiole and leaf blade epidermis is unilayered, with a papillose upper side, which is covered by a thin cuticle. The paracytic stomata occur at the same level as the other epidermic cells. The mesophyll is constituted by a single layer of palisade parenchyma and several layers of spongy parenchyma. Subepidermic chollenchyma is observed on the upper and lower sides of the midrib and on the margin of the blade. The "U" shaped collateral vascular bundle is distributed along the petiole and midrib, and always sided by two smaller vascular bundles, laterally located. Cortical aerenchyma is observed in the petiole and midrib. The anatomical characteristics follow the pattern described for the Rubiaceae with some of them being interpreted as adaptations to moist and shady environments where the species occurs.
leaf anatomy; Palicourea; Rubiaceae; shade leaves
