Edna Scremin-Dias

Micromorphology and anatomy of the leaf blade: a contribution to the taxonomy of Luziola (Poaceae, Oryzoideae) from the Pantanal, Brazil

Luziola comprises nine monoecious, aquatic species and has its center of diversity in South America. Due to the morphological similarities among Luziola species in the vegetative stage, the micromorphology and anatomy of the leaf blade of five Luziola species were studied to survey potentially useful features for taxon identification. Oryzoid silica bodies; silicified unicellular trichomes with a rounded apex; stomata in furrows on the adaxial surface; a complex midrib consisting of at least two vascular bundles; superposed vascular bundles in the mesophyll; and fusoid cells are features shared by some of these species. Conversely, features unique to a single species include: vertically elongated epidermal cells surrounding pointed unicellular trichomes, flat midrib and leaf margin dimorphism (L. fragilis), and an obtuse leaf blade margin (L. subintegra). L. spruceana and L. subintegra show the greatest micromorphological and anatomical affinity among the five species herein studied, and L. fragilis has the greatest number of unique features. All species are recognized by the structure of the midrib, a strong feature for the identification of taxa within Luziola. A key for the identification of the studied species is presented based on the leaf blade features.

Composição florística e variação sazonal da biomassa de macrófitas aquáticas em lagoa de meandro do Pantanal

Neste estudo e descrita a composicao floristica e analisada a influencia do pulso de inundacao sobre a biomassa de quatro especies de macrofitas aquaticas, Eichhornia azurea, E. crassipes, Pistia stratiotes e Salvinia auriculata, ao longo de um ciclo hidrologico, em uma lagoa de meandro no Pantanal Mato Grosso do Sul. Foram identificados 42 taxons, inseridos em 34 generos e 25 familias botanicas. As maiores riquezas foram obtidas para as familias Araceae, Onagraceae e Poaceae, com quatro especies cada, 14 familias apresentaram apenas uma especie, e o genero mais representativo foi Ludwigia, com quatro especies. Das formas biologicas, a que foi representada pelo maior numero de taxons foi a emergente, seguida da anfibia e flutuante livre. As especies analisadas apresentaram diferencas significativas ao longo do periodo sazonal nas duas regioes de amostragem (p < 0,05). Mesmo nao apresentando padrao na variacao temporal da biomassa de todas as especies estudadas, houve relacao da biomassa de E. azurea e E. crassipes a flutuacao do nivel da agua da lagoa.

Effects of Flood Pulse Dynamics on Functional Diversity of Macrophyte Communities in the Pantanal Wetland

Environmental variations and plant traits can act as a filter in plant communities, selecting better-adapted species. In wetlands, macrophytes display physiological, morphological and life history plasticity that allows them to adapt to flood dynamics reflecting habitat filtering. Our aim was to evaluate if the functional diversity of macrophytic community varies between the flood phases, noting whether water factors influence the functional diversity and whether the traits that denote adaptation are associated with these phases. We evaluated 11 morphological traits of macrophytes. The floristic survey within and on the edge of twenty ponds was carried out on a monthly basis and the water parameters were measured for two years. The functional diversity was lower in the ‘drought’ and increased over the flood cycle reaching maximum values in the ‘water recession’ phase. ‘Drought’ acted as a filter by selecting only a few adapted species and the ‘water recession’ acted as a transition area combining favourable conditions for the species of both dry and flood. The trait that contributed most to differentiate the functional groups was the life form. We conclude that the environments under spatial and temporal changes support different communities with different functional characteristics.

Leaf traits, sclerophylly and growth habits in plant species of a semiarid environment

Plants that grow in semiarid environments can sustain a positive equilibrium between water absorption and loss. This equilibrium is reminiscent of structural traits acquired throughout their evolutionary history. Woody species often possess sclerophyllous characteristics when growing in dry environments. Herbs on the other hand commonly shed leaves during unfavorable conditions, such as drought, allowing them to grow and establish themselves rapidly, and therefore are less sclerophyllous. Based on observations of species representing different growth habits, and considering xeric habitats, we raised the hypothesis that woody species will posses sclerophyllous traits and that these traits will vary among growth habits. We evaluated morphoanatomical traits that were previously described in the literature as being adaptations to arid environments, of 16 species, of four different growth habits, that co-occur in the Brazilian “Chaco”. Only vine species showed adaptive convergence to dry environments. Woody species were found to possess sclerophyllous traits, including thicker leaves, well-developed palisade parenchyma and the presence of sclerenchyma. Herbaceous species exhibited mesomorphic traits, including larger leaves and little or no sclerenchyma. We concluded that all the analyzed species possess adaptations to the dry environment, although not all of them are sclerophyllous. As expected, woody species and herbaceous species possess different strategies for adapting to environmental conditions.

MORFOLOGIA DOS DIÁSPOROS, GERMINAÇÃO E DESENVOLVIMENTO DAS FASES JUVENIS DE Adelia membranifolia (MÜLL. ARG.) PAX & K. HOFFM. (EUPHORBIACEAE)

Adelia membranifolia (Mull. Arg.) Pax & K. Hoffm. e uma arvore de pequeno porte, dioica, com distribuicao restrita a America do Sul, sendo a unica especie do genero Adelia L. (Euphorbiaceae) com ocorrencia no Brasil, frequente e abundante na floresta riparia do rio da Prata, regiao sudoeste de Mato Grosso do Sul. Este estudo descreve os aspectos morfologicos dos frutos, das sementes e o desenvolvimento das fases juvenis de Adelia membranifolia e analisa o padrao de nervacao foliar das plantas jovens visando contribuir com o conhecimento biologico e auxiliar na identificacao da especie em ambiente natural. O fruto e esquizocarpico, seco, de coloracao amarelada, tricoco, mede em media 6,71 mm (± 0,51) de comprimento, 10,11 mm (± 0,78) de largura e pesa 0,42 g (± 0,12). A dispersao primaria e autocorica e as sementes possuem forma globosa, coloracao acinzentada, caruncula rudimentar, medem em media 3,90 mm (± 0,20) de comprimento e 3,76 mm (± 0,23) de largura. A taxa de germinacao e de aproximadamente 90 % em câmara de germinacao e 80 % em viveiro de mudas. A germinacao e do tipo fanerocotiledonar epigea e o desenvolvimento das plântulas ocorre entre 5 a 15 dias. Os cotiledones e eofilos apresentam nervacao do tipo pinada com padrao camptodromo broquidodromo.

Erratum to: Meristematic activity of the endodermis and the pericycle in the primary thickening in monocotyledons. Considerations on the "PTM" [An Acad Bras Cienc 77(2005): 259-274]

of trace metal toxicity using molecular, physiological and behavioural Instituto de Biociencias