In Pterodon pubescens the primary and secondary pulvini show structural peculiarities in relations of petiole and rachis. These peculiarities include thicker cuticule, more developed cortex with only parenchyma cells with irregular shape, central vascular tissues, presence of septate fibers around the phloem, and absent or reduced pith. Petiole and rachis show reduced cortex constituted by parenchyma isodiameters cells, peripheric vascular tissues surrounded by gelatinous fibers and pith. Phenolic compounds were detected inside vacuole of parenchyma cells of the pulvinus. Starch grains were observed in the parenchyma cells of petiole and rachis. The features of P. pubescens pulvinus are common to pulvini of others species of Fabaceae, and have been associated to the intensification of lateral changes of ion and water between cortical cells and vascular tissues, besides to provide more flexibility and movement capacity of this organ. On the other hand, the features of petiole and rachis give more rigidity to these leaves structures.
anatomy; petiole; Pterodon pubescens; pulvinus; rachis
