The secretory structures of Alismataceae have been described as secretory ducts, laticifer ducts, laticifer canals or schizogenous ducts. However, these terms are not found in the specialized literature, and ontogenetic analyses for the exact classification of these structures are missing. Accordingly, more studies regarding the secretory structures of Alismataceae are necessary to establish homology in the family or in the order. Thus, the aim of this study was to describe the anatomy, ontogeny, distribution in the organs and exudate composition of the secretory structures present in five Alismataceae species in order to determine whether the family has laticifers or secretory ducts. Samples of leaves, flowers and floral apices were processed for anatomical and histochemical analyses by light microscopy. The analysis indicated the presence of anastomosing secretory ducts in all species, occurring in both leaves and flowers. The exudate contains lipids, alkaloids, proteins and polysaccharides, including mucilage. The secretory duct structure, distribution and exudate composition suggest a defense role against herbivory and in wound sealing. The presence of secretory ducts in all species analyzed indicates a probable synapomorphy for the family.

Se describen las características anatómicas de la epidermis foliar y mesófilo de las especies Cecropia longipes, C. membranacea y C. peltata. El material vegetal fue recolectado en Córdoba- Colombia. Se realizaron disociaciones epidérmicas y cortes transversales de la lámina media mediante técnicas histológicas convencionales. Los caracteres evaluados: forma y el contorno de las células epidérmicas, indumento aracnoideo abaxial, organización de las células de la base de los tricomas, idioblastos epidérmicos, tipo y distribución de los estomas, mostraron diferencias que permiten separar a C. membranacea de las otras especies. Las especies C. longipes y C. peltata son similares en la anatomía de la lámina foliar, sin embargo, es posible distinguirlas teniendo en cuenta la epidermis pluriestratificada y proporción del parénquima clorofiliano, aunque estas características no se presentaron en todas las muestras. Los caracteres evaluados son útiles desde el punto de vista taxonómico y pueden contribuir a la identificación de las especies de la tribu Cecropieae.

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