Diversity and evolution of secretory structures in Sapindales

Sapindales comprise nine families with a mainly tropical distribution and include numerous species of high economic importance. Members of this order are known for the production of chemical constituents with medicinal properties, such as antioxidant, anti-inflammatory, and antimicrobial activity, as well as species with insecticidal properties. Such diversity of chemical compounds is attributed to a variety of secretory structures, which may occur in both vegetative and reproductive organs. During the past decades, tremendous progress has been made in anatomical and analytical chemistry studies, which has led to the next level of knowledge regarding the secretory structures of Sapindales. This comprehensive review embraces the most important data of the secretory structures of Sapindales: ducts, cavities, laticifers, floral and extrafloral nectaries, osmophores, colleters, idioblasts, and trichomes. Our review comprises structural, functional, and evolutionary aspects of these glands, which are fundamental for further studies of the diversification within Sapindales.