ABSTRACT Floral secretory structures are usually associated with the attraction of pollinators, but may also play an important role in the mechanisms of plant protection. This study aimed to show the diversity of secretory structures present in the developing flowers of 15 legume species belonging to different clades and to associate them with functions other than the pollinator attraction. Buds, flowers and developing axis of inflorescence were processed for surface, histological, and ultrastructural analyses. The species investigated displayed a wide diversity of secretory structures in developing flowers such as phenolic cells and/or tissues, mucilaginous cells, secretory cavities, secretory trichomes and colleters. Each type of secretory structure exhibited variation in morphology and location in the flower and/or axis of inflorescence depending on the species. Special mucilage cells, secretory cavities, secretory trichomes and colleters have great potential for comparative morphological studies due to their diversity of forms or restricted occurrence to certain taxa, contributing to a more robust morphological data base for the new clades emerging in Leguminosae. The scarcity of reports about floral secretory structures of Leguminosae seems to be more related to deficient sampling than to the absence of such structures in the group, which highlights the need for further investigation.

O objetivo deste trabalho foi estudar, usando microscopia de luz e de fluorescência e microscopia eletrônica de varredura, a morfologia e o material secretado de tricomas glandulares de Cordia verbenacea DC. (Boraginaceae), conhecida como erva-baleeira, uma espécie utilizada na medicina tradicional como anti-inflamatório, analgésico, anti-úlcera e cicatrizante. Duas classes de tricomas glandulares foram reconhecidas, globular e reniforme. O estudo morfológico da cabeça secretora e a caracterização do material secretado também são apresentados. A secreção dos tricomas globulares caracteriza-se como óleo essencial, enquanto que nos reniformes consiste basicamente de compostos fenólicos, como flavonóides. Nenhuma região pré-estabelecida para a liberação da secreção foi encontrada.

The objective of this work was to study, using light and fluorescence microscopy and scanning electron microscopy, the morphology and secretory products of glandular trichomes of Cordia verbenacea DC. (Boraginaceae), known as 'baleeira', a species used in folk medicine as anti-inflammatory, analgesic, anti-ulcerogenic and healing agent. Two classes of glandular trichomes were recognized, globular and reniform. A morphological study of the secretory head and the characterization of the secretory product are also presented. Secretory products of globular trichomes consisted of essential oils, whereas reniform trichomes consisted basically of phenolic compounds such as flavonoids. No pre-established regions for releasing secretory products were found.