Palavras-chave: metabólitos secundários, plantas tóxicas, ecologia química, monilophyta, licophytaABSTRACT -(Cyanogenesis in sporophytes of pteridophytes evidenced by the picric acid test). Cyanogenic glycosides are defense substances found in some plants that are able to produce cyanhydric acid on hydrolysis. The present work aimed to study the occurrence of cyanogenesis in pteridophytes of rocky areas of Pedra de Itacoatiara, State Park of Serra da Tiririca, Rio de Janeiro State. Nineteen species, distributed in 13 genera and nine families have been analyzed monthly, during one year. In each species, the analysis was carried out on fertile leaves, sterile ones, young leaves (croziers) and stems. Cyanogenesis was evidenced using filter paper embedded with picric acid. Among studied species, 14 were analysed here for the first time, and 14 gave a positive picric test. Our results showed variation along time in the production of cyanhydric acid in the vegetal species and parts. The species, Microgramma vacciniifolia (Langsd. & Fisch.) Copel. (Polypodiaceae) and Pteridium aquilinum (L.) Kuhn var. arachnoideum (Kaulf.) Brade (Dennstaedtiaceae) were cyanogenic all along the studied period.

RESUMO -(Variação intraespecífica do lenho de Pseudopiptadenia contorta (DC) G.P. Lewis & M.P. Lima (Leguminosae -Mimosoidae) ocorrentes em dois remanescentes de Mata Atlântica). O presente trabalho compara populações distintas de Pseudopiptadenia contorta (DC.) G.P. Lewis & M.P. Lima ocorrentes em dois remanescentes de Floresta Atlântica no Estado do Rio de Janeiro. Foram amostradas árvores de diâmetro semelhante retas e sem defeitos aparentes. Os resultados obtidos comprovam estatisticamente a ocorrência de variação intraspecífica na estrutura anatômica da madeira. Os caracteres qualitativos mantiveram-se constantes, enquanto os quantitativos variaram, sendo os significativos, de acordo com o teste t de Student, a freqüencia, comprimento e diâmetro dos elementos vasos, o comprimento e espessura da parede das fibras, a freqüência e largura dos raios. A análise dos componentes principais, utilizando características anatômicas quantitativas ordenou as duas populações separadamente. O eixo I responde por 33% da variância total principalmente pela relação positiva do diâmetro do elemento de vaso, enquanto o eixo II responde por 20% da variância total, principalmente pelo comprimento das fibras. Palavras-chave:Pseudopiptadenia, anatomia da madeira, Leguminosae, variação intraspecífica ABSTRACT -(Intraspecific variation in wood anatomy of Pseudopiptadenia contorta (DC) G.P. Lewis & M.P. Lima (LeguminosaeMimosoidae) in two Atlantic rain forest remnants). This study compares distinct populations of Pseudopiptadenia contorta (DC) G.P. Lewis & M.P. Lima occurring in two remnants of Atlantic rain forest in Rio de Janeiro state. Trees with similar diameters and with no apparent defects were selected. The results confirm intraspecific variation in wood anatomy. Qualitative features do not change, while according to the Student t test quantitative features showed significant differences in vessel-element frequency, width, and length, fiber length and wall thickness, and ray frequency and width. Principal component analysis showed two separate populations. Factor 1 explains 33% of the total variance, mainly due to the positive relationship of vessel-element tangential diameter; factor 2 explains 20% of the total variance, mainly due to fiber length.

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