Essa dissertação foi subdivida em cinco capítulos que, apesar de relacionados entre, podem ser lidos e compreendidos de forma independente. O primeiro capítulo trata de um breve histórico sobre o espessamento primário em caules de monocotiledôneas. Seu principal objetivo é deixar evidente para o leitor a problemática referente tanto à nomenclatura dos tecidos relacionados ao espessamento primário em monocotiledôneas, quanto explicar as hipóteses que embasam essas nomenclaturas. O segundo capítulo teve como principal objetivo evidenciar que, apesar da discordância de muitos autores da atualidade, existe continuidade dos tecidos endoderme e periciclo entre os órgãos no corpo vegetativo de monocotiledôneas, apresentando indícios que apóiam esse pensamento. Já o terceiro capítulo, Caule, demonstra dados que corroboram o pensamento defendido nessa dissertação: endoderme e periciclo são os tecidos responsáveis pelo espessamento do corpo primário do caule de monocotiledôneas. O quarto capítulo, Folha, discute e demonstra a presença de endoderme (entorno da unidade vascular desse órgão) e periciclo (como parte dessa unidade vascular) em folhas de Zingiberaceae e Costaceae. O quinto e último capítulo aborda a importância dos já mencionados tecidos, quais sejam endoderme e periciclo, na formação da raiz primária.

Since ends of 19^th century, arised a great diversity of terminologys to name meristematic region responsible for primary thickening in monocotyledons. Despite of this great number of denominations, a few hypothesis and ideas are utilized to base this great complex of terminologys. This historical chapter aims explain the origin from this terminologys and understand correlations between hypothesis basis. At the end of this explanation, you can understand why the defense of presence of endodermal and pericycle tissue as the two meristematic tissues responsible for this primary thickening in monocotyledonous rather than the currently most accepted name of "PTM", a single meristem advocated by many authors. Despite of many authors consider fact the continuity between the vascular tissues of stem and leaf and stem and root, few authors consider that the endodermis (between stem and leaf and between stem and root) and pericycle (between stem and leaf and stem and between root) of these organs may be continuous. It was shown, with verification of the continuity of the tissues mentioned above, the plant is a unit and can be found in the root and leaves the same tissues found in the stem, in this case, the main tissues examined in this chapter: endodermis and pericycle. This chapter aims to discuss, demonstrate, and finally prove the continuity of the tissues mentioned in Zingiberaceae, and also describe the morphology of these tissues in each of the aforementioned organs. The stems of monocots has been the subject of studies since the nineteenth century. But despite the large amount of work produced since then, there is still controversy regarding the primary tissue responsible for thickening of this organ. The families Zingiberaceae Costaceae and serve as a model for which more data were collected showing not only the presence of endodermis and pericycle in the stem, but also to show that these are the meristematic tissues responsible for primary thickening in this organ. It was observed in the underground stem, the presence of strips of Caspary in the region farthest from the apex. Already in the air stem, the endodermis was seen only parenchymatous, without any morphological alteration in its walls. The meristematic pericycle was found in the underground stem, but in the aerial stems it is pluriseriated and have cell walls thick. Many authors recognize that the leaf is a projection of stem. But despite this recognition of the origin of this organ, few authors admit that there is continuity between the tissue found in these two organs. This chapter aims to show that tissue found in the stem, which are endodermis and pericycle, are also present in the leaves of species of Zingiberaceae and Costaceae families. Although not possible to observe strips of Caspary involving the vascular unit found in the leaves, could be observed in leaf expansion an accumulation of phenolic substances in tissue, facilitating the visualization of the cells corresponding to the endodermis. The pericycle, forming pericycle fibers was also observed and described. The root is one of the most preserved organs of all vegetative organs of vascular plants. This is the only organ where the tissues endodermis and pericycle are found in any textbook and that are part of primary body of the root. But despite this recognition, the endodermis is not seen by the authors in general, as being important for the formation of the root cortex. This chapter shows the presence of endodermis with meristematic activity, and demonstrate its derivatives (DEMs) in the root cortex of species of families Zingiberacaea and Costaceae.