Marinês Ferreira Pires Lira

The aim of the study was to evaluate the effect of different light conditions on the internal structure of Piper aduncum L. leaves. P.aduncum seedlings were grown for 4 months under different light conditions achieved with shading nets (50, 70, and 100% of luminosity) and with photoconversion nets in red (RN) and blue (BN) colors. Two fully expanded leaves located at the third node were collected from five plants per treatment for paradermal and transverse sections. In the paradermal sections, stomatal density, polar and equatorial diameters, the ratio between polar and equatorial diameters, and trichome density on the abaxial and adaxialsurfaces of the epidermis were evaluated. In the transverse sections, the thickness of the adaxial and abaxial epidermis, cuticle of the adaxial surface, palisade and spongy parenchyma, and leaf blade were assessed. The vessel elements parameters were also evaluated and Carlquist vulnerability index were measured. The results show that P. aduncum changes the internal structure of its leaf when grown under different radiation conditions. It presented greater epidermis thickness, greater stomatal density and smaller diameters of vessel elements, anatomical characteristics favorable to its growth under high irradiances.

Seasonally Dry Tropical Forests experience pronounced precipitation seasonality, intense solar radiation, and high temperatures, which often translate into high levels of deciduousness during the dry season. In these environments, deciduous species coexist with some evergreen species that are able to maintain their canopy leaves throughout the dry season. To understand the strategies behind this behavior, we analyzed leaf anatomical traits of 13 individuals of Sarcomphalus joazeiro during both the wet and dry seasons in a seasonal deciduous forest. We hypothesized that wet-season leaves would differ anatomically and functionally from dry-season leaves. Specifically, we expected wet-season leaves to show a more acquisitive resource-use strategy compared to dry-season leaves, which we expected to be more conservative. We assessed the effects of season and climatic variables on 25 leaf anatomical traits using generalized linear mixed models (LMM). Leaf traits varied between the wet and dry seasons and interacted with climatic variables, which together suggest that S. joazeiro produces season-specific leaf cohorts. This adaptation allows the species to adjust to the contrasting conditions of light intensity, temperature, and evaporative demand in each season.

Erythroxylum is common in the Brazilian Cerrado. Species from this genus have ecological, pharmacological and popular medical importance. Based on this information, the aims of this study was to perform a descriptive and quantitative morphoanatomical study of Erythroxylum tortuosum leaves present in two environments: cerrado sensu stricto and campo rupestre. To carry out these studies, 24 fully developed leaves were collected and fixed from individuals across both environments. For the quantitative anatomy study, the following measurements were made: leaf area, length, width and mass; stomatal density; polar and equatorial diameter of the stomata; thickness of the leaf blade, mesophyll, epidermis and cuticles on the adaxial and abaxial surfaces; and thickness of the spongy and palisade parenchyma; specific leaf area, leaf mass area and foliar tissue density. This species shows a bald and uniseriate epidermis when viewed in cross section. Stomata are paracytic and occur only on abaxial surfaces. The mesophyll is dorsiventral type, with a dense vascular system, and the vascular bundle is collateral type. The general pattern of the veins is pinnate camptodrome and brochidodrome, with dense veins and pseudosecondary ribs. Significant differences were found for almost all analysed variables, suggesting that different environmental conditions may influence plant development.

The genus Eremanthus (Asteraceae) covers mostly arboreal species, popularly known as “candeia”. Three of these species, E. erythropappus, E. incanus and E. glomerulatus, are endemic to and extensively distributed in Brazil. “Candeias” are of commercial interest due to the good quality of their wood and, mainly, to their essential oils, used for various therapeutic purposes. These species of “candeia” have similar vegetative characteristics, mainly to E. erythropappus and E. incanus, making them difficult to differentiate in the field. This study aimed to characterize the anatomy and external morphology of these “candeia” species to facilitate identification. Qualitative and comparative analysis of the anatomy, histochemistry and ultrastructure of the leaf surface and the external morphology of the leaves were performed. The greatest differentiation between the three species was possible through the external morphological characteristics. The most representative characters were used to elaborate a dichotomous key.

Para verificar a influência da altitude na estrutura anatômica de folhas e do xilema secundário de galhos de indivíduos da espécie Clethra scabra Pers. (Clethraceae) ocorrentes na Serra da Mantiqueira, estado de Minas Gerais, realizaram-se coletas de amostras nas cotas altitudinais de 1500, 1700, 1900 e 2100 m (metros). As folhas e galhos coletados foram fixados e preparados seguindo procedimentos usuais de microtécnica vegetal. Procederam-se análises anatômicas quantitativas utilizando software de análise de imagem. As folhas de C. scabra são hipoestomáticas com epiderme trisseriada e tricomas estrelados, mesofilo dorsiventral, parênquima paliçádico com uma a duas camadas celulares e o parênquima esponjoso com quatro. A nervura central com xilema desenvolvido e o feixe vascular envolvido pela bainha esclerenquimática. Análises de variância (ANOVA) e teste de Scott-Knott demonstraram que as espessuras do limbo foliar, mesofilo e parênquima paliçádico não apresentaram diferenças estatísticas significativas entre as altitudes avaliadas. O xilema secundário apresentou diminuição no comprimento dos elementos de vaso com o aumento da altitude na cota de 2100 m e o diâmetro tangencial dos elementos de vaso aumentaram nas duas menores altitudes e depois reduziram. Índices de vulnerabilidade de Carlquist e de mesomorfia diminuíram ao longo do gradiente altitudinal. Comprimento e diâmetro das fibras diminuíram com elevação da altitude. Assim, a altitude influencia nas modificações anatômicas apresentadas por folhas e galhos de C. scabra, que podem ser relacionadas a sua plasticidade fenotípica em resposta às diferentes condições ambientais.