RESUMOPiper L. (Piperaceae) é monofilético, com espécies de difícil distinção taxonômica, sendo necessários ferramentas que auxiliem a identificação interespecífica. Os objetivos do trabalho foram descrever os macropadrões e caracterizar in situ a composição química dos cristais caulinares e foliares de Piper arboreum Aubl. var. arboreum, P. callosum Ruiz & Pav. e P. tuberculatum Jacq., visando avaliar o uso dos cristais para a separação interespecífica. Para tanto, amostras foram submetidas à análise em microscopias de luz e eletrônica de varredura, microanálises espectroscópicas de raios-X por dispersão de energia e testes histoquímicos. Foram observados cristais prismáticos cuneiformes, tabulares, cúbicos e bipiramidais; ráfides; estiloides; drusas de cristais em bloco; rosetas cristalinas de estiloides e concrescências cristalinas. Foram descritos 15 macropadrões cristalinos reunidos em três categorias. Os cristais foram classificados quimicamente como: puros de oxalato de cálcio e misturas entre oxalatos e sulfatos e entre oxalatos, sulfatos e sílica. Rosetas cristalinas, concrescências cristalinas silicificadas e 14 dos 15 macropadrões cristalinos descritos são registros inéditos para inclusões biominerais de Piper e Piperaceae. Os macropadrões cristalinos caulinares e foliares observados são constitutivos e úteis à separação interespecífica das espécies estudadas. Ademais, os cristais desempenham funções relevantes para a autoecologia dos taxa de Piper analisados. PALAVRAS-CHAVE: Cristais, MEV-EDS, Histoquímica, Quimiometria. Silicified crystal concretions and rosettes in Piper (Piperaceae): unpublished reports on their macropatternsABSTRACT Piper L. (Piperaceae) is monophyletic, with species of difficult taxonomic distinction, and thus tools that facilitate interspecific identification are needed. The aims of this study were to describe the macropatterns and characterize in situ the chemical composition of leaf and stem crystals of Piper arboreum Aubl. var. arboreum, P. callosum Ruiz & Pav. and P. tuberculatum Jacq., in order to evaluate the use of the crystals on interspecific distinction. Samples were submitted to analyses under light and scanning electron microscopies, energy-dispersive x-ray spectroscopic microanalyses, and histochemical tests. We observed cuneiform, tabular, cubic, and bipiramidal prismatic crystals; raphides; styloids; blocky crystal druses; styloid crystal rosettes; and crystal concretions. We described 15 crystal macropatterns, which were distributed along three categories. The crystals were chemically classified as: pure calcium oxalate; and mixtures of oxalates and sulfates, and of oxalates, sulfates and silica. Crystal rosettes, silicified crystal concretions, and 14 out of the 15 macropatterns described are unpublished reports on biomineral inclusions in Piper and Piperaceae. The stem and leaf crystal macropatterns observed are constitutive and useful for interspecific separation of the studied species. Moreover, the crystals present relevant functions for the autecology of t...

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Although taxonomic studies indicate that approximately one-third of the genera of Polygalaceae have nodal glands, few anatomical data are available on the structure and ontogeny of these secretory organs. We studied the as yet unknown origin, structure and function of such glands in Polygala laureola. During field observations, we detected glucose in the secretion using Glicofita Plus® and visitors were recorded. Vegetative shoot apices and nodal glands were examined using light microscopy and scanning electron microscopy. The presence of glucose in the secretion allowed us to identify these nodal glands as extranuptial nectaries. Secretory cells occupy a medullary position and are surrounded by phloem. Vascular bundles are concentric, and xylem is only observed at the basal region of the nectary. Nectar is released during the daytime through a pore at the top of the nectary. A stipular origin was confirmed by the fact that the procambial strand is connected to the leaf trace, opposite the leaf gap. The occurrence of stipular extranuptial nectaries in a nodal position is new to Polygala.