Occurrence, structure and functional aspects of the colleters of Copaifera langsdorffii Desf. (Fabaceae, Caesalpinioideae).

Reports concerning colleters in Fabaceae have been scarce, mainly in the Caesalpinioideae subfamily. The present work reports the occurrence, structure, and functional aspects of the colleters of Copaifera langsdorffii. Shoot apices and developing leaves were fixed and processed for examination by light and electron microscopy. Secretion samples were studied to determine their chemical nature and physical properties. The colleters are clavate and occur on the adaxial face of the stipules, petiole and rachis. The secretory stage of the colleters occurs during the leaf expansion, after which these structures turn brown and senesce. The secretion is composed of highly hygroscopic acidic polysaccharides and lipids. The colleters are composed of cells with thin walls, large nuclei, and dense cytoplasm with dictyosomes, mitochondria, plastids and the endoplasmic reticulum. Analyses of the secretion, placement, and functional aspects of the colleters present in C. langsdorffii indicate that these structures help protect young leaves from desiccation.