https://repositorio.ufu.br/handle/123456789/18960 Sat, 10 Oct 2026 07:32:23 GMT 2026-10-10T07:32:23Z https://repositorio.ufu.br/handle/123456789/50469 Title: Micromorfologia e anatomia da lâmina foliar do complexo Saccharum (Poaceae - Andropogoneae) Abstract: In a broad sense, the genus has about 40 species and is related to other genera due to morphological similarities and phylogenetic proximity between them, composing the Saccharum complex. The genera that compound the group are: Erianthus, Lasiorhachis, Miscanthidium, Miscanthus, Narenga, Saccharum, Sclerostachya and Tripidium. Sugarcane (Saccharum officinarum), of great importance for the world economy, is included in the genus Saccharum. This study aimed to investigate the micromorphology and comparative leaf anatomy of Saccharum and related genera, in order to contribute with data to the taxonomy of the group. Anatomical analyses of the median leaf region were performed under an optical microscope for 41 species from all genera within the Saccharum complex. The samples were obtained from herbarium material and prepared according to standard methods of plant anatomy. Micromorphological analysis was conducted using a scanning electron microscope (SEM). Histological slides were photographed to record the results using a light microscope with an attached digital camera. Features such as the presence of microtrichomes, prickles, and short cells were observed in all analyzed species. However, the genera exhibited distinct patterns in some characteristics, such as the arrangement of buliform cells, number of layers and nature of the bundle sheath, and the presence of colorless cells just below the epidermis. Additionally, anatomical differences were observed within Erianthus between species from South America and those from North America. For the Old World species, there was considerable variation in anatomical characteristics among the species. Lasiorhachis and Tripidium, despite being phylogenetically distant from the other genera in the Saccharum complex, share many anatomical characteristics with them. This study demonstrates that micromorphology and leaf anatomy are of great importance in assisting the delimitation of taxa within the Saccharum complex. Fri, 28 Jul 2023 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50469 2023-07-28T00:00:00Z https://repositorio.ufu.br/handle/123456789/50347 Title: Aclimatação morfofisiológica da liana Rhynchosia melanocarpa Grear. ao aumento da intensidade de luz Abstract: Phenotypic plasticity in response to variations in light availability is a key factor determining the establishment of seedlings in heterogeneous environments. This study evaluated the ecophysiological, photosynthetic, and growth responses of Rynchosia melanocarpa, a liana with a wide distribution among distinct kinds of vegetation physiognomies, such as Cerrado and Atlantic rain forest. The seedlings were subjected to three light conditions: full sunlight (FS), shade (SH), and transfer from shade to full sunlight (SH→FS). Chlorophyll a fluorescence, electron transport rate (ETR), Falker Chlorophyll Index, gas exchange, growth indices, and biomass allocation were assessed. Seedlings maintained under shade exhibited high maximum quantum yield of PSII (Fv/Fm ≈ 0.80), higher chlorophyll content, greater specific leaf area, and higher leaf area ratio, reflecting typical acclimation responses to low irradiance. Conversely, seedlings grown under full sunlight showed higher net CO₂ assimilation, increased electron transport rates, greater water-use efficiency, enhanced carboxylation efficiency, and greater biomass allocation to roots. The transfer from shade to full sunlight induced marked initial photoinhibition, evidenced by a sharp decline in Fv/Fm and effective quantum yield (ΔF/Fm'), accompanied by temporary leaf chlorosis. However, after 24 days, transferred plants showed partial recovery of photochemical efficiency, increased electron transport rate, and maintenance of high photosynthetic performance, indicating successful acclimation to the new light environment. These seedlings also exhibited relative growth rates comparable to those grown under full sunlight and greater height increment, suggesting preferential investment in vegetative growth during acclimation. Overall, the results demonstrate that R. melanocarpa possesses high physiological and morphological plasticity, combining conservative strategies under shade with high photosynthetic performance under full sunlight. This functional flexibility enables rapid recovery following abrupt changes in irradiance, highlighting the ecological potential of the species to establish across contrasting light environments, a characteristic commonly associated with pioneer or early secondary tropical tree species. Sun, 30 Aug 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50347 2026-08-30T00:00:00Z https://repositorio.ufu.br/handle/123456789/50195 Title: Tendências evolutivas no androceu de Melastomataceae: estudos morfológicos e anatômicos dos estames e anteras em gêneros de Melastomeae Abstract: Members of Melastomataceae family usually have actinomorphic and bisexual flowers. The most important pollinator of the plants of this family is female bees which are able to vibrate its poricidal anthers and remove pollen, although there are spontaneous self-pollination species and also apomitic species. In addition to this diversity of reproductive systems, variations throughout the development of the anther wall can take place, ensuing in diversification of parietal layer composition. However, most studies have focused on individuals of the Miconieae tribe; hence there is a necessity to look into these variations in other tribes, specially the most representative in Brazil among them, the Melastomeae. Thus, an objective of this study was to describe the morphology and anatomical structure of the stamens in different Melastomeae genera: Acisanthera P.Browne (2 sp.), Comolia DC. (2 sp.), Poteranthera Bong. (1 sp.), Siphanthera Pohl (2 sp.) and Tibouchina Aubl. (5 sp.), attempting to identify and understand, from an evolutionary point of view, the changes found apart from pointing out some features that can assist in the delimitation of these genera and tribes (Chapter 1). This research also aimed to study the floral biology and reproductive system of the smallest species of Melastomataceae known so far, Poteranthera pusilla Bong (Chapter 2). The morphological and anatomical studies, including the vascularization of stamens, were performed according to the usual techniques of plant anatomy; and P. pusilla reproductive biology was studied under control pollination, pollen viability and pollen tube growth. The morphological results have shown that most of the studied species has dimorphic androecium containing ten stamens, which has antesepal stamens larger than antepetals, as well as other members of Melastomeae. But some species have eight stamens of which the four antepetals may be reduced to staminodes, such as S. gracillima. Another modification that has been found is the total loss of one of the cycles of stamens which happens in P. pusilla. During the study about the development of the anther wall, the monocotyledon type was identified on A. genliseoides, A. quadrata, S. foliosa, S. gracillima and T. villosissima and variations of the monocotyledon type have been ascertained on C. lanceiflora, C. sertularia, P. pusilla, T. candolleana, T. herbacea, T. heteromalla and T. stenocarpa. During the whole of microsporogenesis, of all species, the parietal layer of the anther consists of epidermis, endothecium, middle layer and tapetum, differing only in the number of middle layers. At the stage of anthesis just the epidermis is relentless, except for Comolia specieis that also exhibit part of the endothecium. In the course of the vascularization analysis, the trace bundles are larger on antesepals stamens and may be absent on the reduced antepetals, as in A. genliseoides and S. foliosa. These morphological and anatomical studies of the stamens and anthers support the available information up to now about an evolutionary trend towards decreasing the size and number of stamens in Melastomataceae. This decrease, which is apparent on the morphology and the anatomy of anthers and vascularization of stamens, seems to occur separately within each genus and shall be related to a sort of pollinator. The study of reproductive biology has shown some morphological characteristics in P. pusilla that allow spontaneous self-pollination, such as large pores and the arrangement of the stamens of the flower at anthesis. It can be concluded that P. pusilla is self-compatible and that spontaneous self-pollination happens due to the large pore which faces the stigma at anthesis. It is also remarkable, in this species, the independence of biotic factors during pollination and probably over fruits spreading, which culminate in a highly adapted species to survive in environments with scarce pollinators. Considering this scenario, we conclude that all androecium and anthers variations of these species seem to be associated with a general tendency of pollinators in this family, aforementioned for representatives of the Miconieae tribe. Mon, 24 Feb 2014 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50195 2014-02-24T00:00:00Z https://repositorio.ufu.br/handle/123456789/50185 Title: Polinização de Peixotoa tomentosa A. Juss. (Malpighiaceae), como as estruturas florais condicionam a visitação biótica e o transporte polínico Abstract: Plant populations have undergone substantial changes over time due to anthropogenic and climatic factors. Angiosperms are the largest and most diverse plant group and have, accordingly, established extensive mutualistic interactions with insects. In the Cerrado, plant–insect interactions are highly diverse, and among the most relevant in this context are those involving the family Malpighiaceae, one of the 11 botanical families that produce floral oils. We investigated how floral morphology in one of its species, Peixotoa tomentosa A. Juss., affects bee visitation and fruit set, considering its capacity to produce fruit through agamospermy. The study was conducted in a Cerrado fragment at Itororó Park Club (formerly Clube de Caça e Pesca Itororó), in Uberlândia, Minas Gerais, Brazil. We assessed floral attractiveness to small-, medium-, and large-bodied bees and the resulting fruit set, and tested five controlled pollination treatments. Visitation rate was lower than expected, with only 10 bees recorded over 15 hours of observation, which limited the evaluation of the floral attraction and fruit set hypotheses; this did not, however, preclude comparison among pollination treatments, whose fruit set values were statistically similar, indicating reproductive capacity even in the absence of pollen grains. Although the adhesive function of staminodes has previously been reported in other plant families, our study provides the first confirmation of this function within Malpighiaceae, showing that the substance exuded by the staminodes significantly increases pollen grain adherence to the transport vector and, subsequently, to the stigmas. Studies on the chemical composition of the staminodal secretion may help elucidate its adhesive function. These results suggest a relationship between low pollinator frequency, prior anthropogenic disturbance (e.g., the 2021 fire), and reduced fruit set, reinforcing the importance of long-term studies on pollination in the Cerrado. Thu, 23 Jul 2026 00:00:00 GMT https://repositorio.ufu.br/handle/123456789/50185 2026-07-23T00:00:00Z