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We investigated the presence and orientation of peripheral vascular bundles in leaves of 81 species representing 72 genera of Aizoaceae. Our study included a wide range of morphological shapes of leaves sampled from all four subfamilies of Aizoaceae, with an emphasis on succulent leaves found in Mesembryanthemoideae and Ruschioideae. Our anatomical studies revealed that only three of the four subfamilies in Aizoaceae have peripheral vascular bundles in their leaves, i.e., Sesuvioideae, Mesembryanthemoideae and Ruschioideae. Apart from Sesuvium (Sesuvioideae), all other species with peripheral vascular bundles have an endoscopic orientation, i.e., the phloem is positioned closer to the epidermis, whereas the xylem is pointing towards the interior of the leaf. This contrasts the situation in other Caryophyllales, where, with the exception of Borszczowia (Amaranthaceae), two different types of three‐dimensional venations were observed. The distinct types of three‐dimensional venation may in turn provide clues to the different pathways by which the similar leaves evolved. Endoscopic peripheral vascular bundles in Aizoaceae were only found in species with an expanded leaf base and (sub‐)cylindrical to trigonous leaves. Although flat‐bladed species of Aizoaceae generally have no peripheral vascular bundles, they were present in Delosperma tradescantioides (Ruschioideae: Ruschieae). Persistent, flat leaves are very rare within the hyperdiverse Ruschieae, which typically have (sub‐)cylindrical to trigonous leaves. Thus, the presence of peripheral vascular bundles in leaves of D. tradescantioides indicates that flat‐bladed, persistent leaves constitute a reversal within tribe Ruschieae. The additional presence of lateral bundles in the outer lamina of leaves of D. tradescantioides can be interpreted as a regain of planate venation. Mapping the evolution of peripheral vascular bundles onto a phylogeny of the Aizoaceae suggests that this character evolved repeatedly within subfamilies Mesembryanthemoideae and Ruschioideae.

AbstrAct:The main goal of this study was to evaluate the performance of two palm species under semi-arid conditions during the rainy and dry periods: the semi-arid native Syagrus coronata and a native to tropical America, Acrocomia aculeata. The leaf water potential, gas exchange, leaf soluble sugars, starch, free amino acids, total soluble protein content and morphological traits were measured.The highest leaf water potential and CO 2 assimilation values in both species were achieved during the rainy period. In response to the low soil moisture content during the dry period, gas exchange when compared with values from rainy period. As evergreen plants, both species maintained intact leaf photosynthetic pigment contents during the rainy and dry periods. Other important traits for drought tolerance are larger adaxial surface hypoderm and cuticle found in both species with higher stomatal density on the abaxial leaf surface.When comparing the species, S. coronata exhibited lower sensitivity to low water availability, showing higher CO 2 assimilation and water use efficiency.

-(Anatomy of the vegetative organs of Cactaceae of the caatinga from Pernambuco). Root and cladode transections of five species of Cactaceae from a "caatinga" of Pernambuco (Harrisia adscendens (Gürke) Britton & Rose; Melocactus × horridus Wedermann; M. zenhtneri (Britton & Rose) Luetzelb.; Tacinga inamoena (Schumann) Taylor & Stuppy, and T. palmadora (Britton & Rose) Taylor & Stuppy), were analyzed to verify diagnostic and adaptative features. The sections were stained with safranin and astrablue and mounted in glycerine. The surveys did not show great differences in the roots inner structure among studied species. In the secondary xylem of the roots broad pericyclic rays occur, representing an important adaptative character in xerophytes. The cladodes present the following diagnostic and adaptative features: type of spines; type and position of stomata; hypodermis structure; presence of crystals in epidermis and hypodermis; type and position of mucilaginous structures; general aspects of the vascular system; occurrence of cortical and medular vascular bundles; and presence of storage parenchyma. The results of this work show that the studied species are typical cacti presenting anatomical features, which can be responsible for the success of these plants in adverse environments as the "caatinga".Key words -anatomy, caatinga, Cactaceae, taxonomy , foram analisadas para verificação de caracteres diagnósticos e adaptativos. As secções foram coradas com safranina e azul de astra e montadas em glicerina. As observações feitas mostraram que a estrutura interna das raízes é bastante similar não sendo observados caracteres diagnósticos. No xilema secundário das raízes ocorrem amplos raios pericíclicos representando um importante caracter adaptativo. O cladódio apresenta os seguintes caracteres diagnósticos e adaptativos: tipos de espinho; tipo e posição dos estômatos; estrutura da hipoderme; tipo e posição das estruturas mucilaginosas; aspecto geral do sistema vascular; ocorrência de feixes corticais e medulares; presença de cristais na epiderme e hipoderme e presença de parênquima aqüífero. Os resultados deste trabalho mostram que as espécies estudadas são cactos típicos apresentando caracteres, que podem ser responsáveis pelo sucesso destas plantas em ambientes adversos como a caatinga. RESUMO -(Anatomia dos órgãos vegetativos de Cactaceae da caatinga pernambucana). Secções de raízes e cladódios de cinco espécies de Cactaceae ocorrentes em uma região de caatinga de Pernambuco (Harrisia adscendens(

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ResumoAnatomia foliar, ultra-estrutura e plasticidade de Coffea arabica L. em resposta à luz e nitrogênio. A plasticidade fenotípica em resposta às variações ambientais ocorre em todos os níveis de organização, em escala temporal dentro da mesma espécie vegetal. Entretanto, a magnitude e a significância funcional desta plasticidade são pouco exploradas em espécies perenes. Nós examinamos a influência de diferentes regimes de luz e concentrações de nitrogênio (N) na plasticidade morfofisiológica de plantas jovens de café (Coffea arabica L.). Os experimentos foram realizados em vasos a pleno sol e sob sombra e fertilizados com solução de Hoagland contendo 0, 16 ou 23mM de N. A maioria das características em reposta à luz demonstram uma clássica distinção entre plantas expostas a pleno sol e sob sombra [e.g. comparadas com as folhas desenvolvidas a pleno sol, as folhas desenvolvidas em 50% de irradiância tiveram um parênquima paliçádico mais delgado e uma menor massa foliar específica (MFE)]. A parede periclinal externa de ambas as faces da epiderme apresenta uma espessa camada de cera epicuticular, composta por três distintas camadas. Os cloroplastos das células do mesofilo são densamente ocupados por tilacóides, além de grãos de amido facilmente visualizados e essa característica é visualizada de forma mais evidente nas plantas cultivadas com suplemento adicional de nitrogênio e à sombra. O índice de plasticidade foi alto para as características fisiológicas associadas à fotoproteção e a manutenção de um balanço positivo de carbono nas plantas aclimatadas a sombra, mas foi baixo para a maioria das características morfoanatômicas. Palavras-chave: Café; Ciclo das xantofilas; Enzimas antioxidantes; Índice de plasticidade AbstractPhenotypic plasticity in response to environmental variation occurs at all organizational levels and across temporal scales within plants. However, the magnitude and functional significance of this plasticity is little explored in perennial species. We examined the influence of different light regimes and nitrogen (N) availability on the morphological and physiological plasticity of coffee seedlings (Coffea arabica L.). Potted plants were grown under full sunlight and shade (50%) and were fertilized with Hoagland's solutions containing 0, 16 or 23mM N. Most leaf traits responded to light with a classic full sunlight vs. shade dichotomy [e.g., compared with those grown under full sunlight, 50% leaves had a thinner palisade mesophyll and a lower leaf mass per area (LMA) for improved light capture]. The outer periclinal cell walls in both epidermises exhibited thick epicuticular wax and three distinct layers. Chloroplasts of the mesophyll cells were densely occupied by thylakoids and starch grains. These characteristics were observed most clearly in plants supplemented by nitrogen or in those grown in shade conditions. Large starch granules were observed, but no membrane injuries were observed in either treatment. The plasticity index was high for the physiological traits that are associated wi...

We investigated whether there were consistent differences in the physiological and anatomical traits and phenotypic variability of an invasive (Prosopis juliflora (Sw.) DC.) and native species (Anadenanthera colubrina (Vell.) Brenan) in response to seasonality in a tropical dry forest. The water potential, organic solutes, gas exchange, enzymes of the antioxidant system, products of oxidative stress and anatomical parameters were evaluated in both species in response to seasonality. An analysis of physiological responses indicated that the invasive P. juliflora exhibited higher response in net photosynthetic rate to that of the native species between seasons. Higher values of water potential of the invasive species than those of the native species in the dry season indicate a more efficient mechanism for water regulation in the invasive species. The invasive species exhibits a thicker cuticle and trichomes, which can reduce transpiration. In combination, the increased epidermal thickness and the decreased thickness of the parenchyma in the dry season may contribute to water saving. Our data suggest a higher variability in anatomical traits in the invasive species as a response to seasonality, whereas physiological traits did not present a clear pattern of response.