The classification of Euphorbiaceae is widely discussed among many authors and now this family is represented by about 300 genera and 6000 species, characterized by having flowers morphologically different, this being one of the main reasons for the differences in its classification. Euphorbiaceae has its representatives divided into four subfamilies, and the species selected for this work belong to three of them: Pera glabrata Poepp. ex Baill., Dalechampia ficifolia Lam (Acalyphoideae), Jatropha curcas L. (Crotonoideae) and Euphorbia caecorum Mart. ex Boiss. (Euphorbioideae). Various secretory structures are found in this group and the species are pollinated mainly by insects, birds, bats and other mammals. Considering the evolutionary changes of flowers and their glands, the purpose of this paper is to analyze the different degrees of floral reduction , with emphasis on the activity of meristems together with the ontogenetic factors which led to suppression of whorls and culminated in the appearance of cyathium and different types of secretory structures in addition to analyze the composition of their exudates. With this purpose, buds and flowers in various stages of development will be collected in different localities of the State of Sao Paulo and Minas Gerais and the species will be identified by a specialist. The material will be fixed, dehydrated in alcohol series, embedded in paraffin, sectioned on a rotary microtome and stained using conventional techniques. Histochemical tests to detect the composition of the exudates will be performed and floral ontogeny will be examined by light microscopy and SEM. Morpho-anatomical knowledge of reproductive organs, secretory structures and floral development provide elements for understanding the evolution of plant groups, including the phylogenetic relationships between them.
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