Leaf surface characters applied to Lauraceae taxonomy in a Seasonal Forest of Southern Brazil

The goal of this work was to test if the macro and micro morphological analysis of the leaf surface could provide vegetative diagnostic characters for some of the most common Lauraceae species in Southern Brazilian Seasonal Forests. The leaf printing technique with universal instantaneous adhesive was used for the epidermical microscopical analysis and external macroscospical analyses of leave were made. Microscopic evaluation revealed the visibility and contours of anticlinal walls of epidermical cell and stomata and shape of guard-cells. Macroscopic evaluation showed the absence or presence of characters such as hairiness, domatia and scents. The results showed that analyzed characters, together with other diagnostic characteristics, could contribute in taxonomic delimitation of some common Lauraceae species in the Southern Brazil.

Este trabalho teve por objetivo testar se a análise macro e micro morfológica da superfície foliar poderia prover caracteres diagnósticos vegetativos para algumas das espécies mais comuns de Lauraceae encontradas em Florestas Estacionais do sul do Brasil. Utilizou-se a técnica de impressão foliar com adesivo instantâneo universal para a análise microscópica da epiderme e procederam-se análises externas macroscópicas das folhas. Microscopicamente, foram utilizados a visibilidade e os contornos das paredes anticlinais das células epidérmicas, bem como a visibilidade dos estômatos e o formato de suas células-guarda. Macroscopicamente, verificaram-se a presença ou ausência de caracteres como pilosidade, domácias e odores. Os resultados obtidos no trabalho mostraram que os caracteres analisados, juntamente com outras características diagnósticas, podem contribuir na delimitação taxonômica de algumas espécies da família comuns no sul do Brasil.

Effects of Pterocaulon polystachyum DC. (Asteraceae) on onion (Allium cepa) root-tip cells

In Brazil leaf infusions of the plant Pterocaulon polystachyum DC (Asteraceae) are used to treat digestive problems. We used plants from six P. polystachyum populations to prepare fresh aqueous leaf infusions at the concentration normally used in Brazil (2.5 g L-1) and at twice (5 g L-1) and four times (10 g L-1) this concentration. We rooted onion bulbs in a water control or one of the infusions for 24 h and used the in vivo onion (Allium cepa) root-tip cell test to investigate the potential mutagenicity of the infusions by calculating the mitotic index for the control and the experimental treatments and comparing them using the Chi-squared test (chi2, p = 0.05). There was a highly significant decrease in the mitotic index of root-tip cells treated with infusion as compared to those exposed to water only. These results indicate that P. polystachyum infusions present cytotoxic and anti-proliferative activity and therefore have therapeutic potential.