Anatomia e perfil lignoídico do lenho e da folhas de Mollinedia schottiana (Spreng.) Perkins

Abstract

The association between chemical and morphological characteristics has allowed the understanding of plant taxonomic, phylogenetic and ecological aspects. This study aimed to characterize wood and leaf anatomy of Mollinedia schottiana, as well as to determine lignin content and chemical composition. M. schottiana is a shrubby-tree species, belonging to the Monimiaceae family, widely distributed over the Atlantic Rain Forest. Five trees with a DBH (diameter at breast height) ≥ 20cm were selected, in a lowland forest at the Tinguá Biological Reserve (22°28 e 22°39 S e 43°13 e 43°34 W), in Rio de Janeiro State. Wood samples were collected 1.30m and 1.35m from the soil, respectively for structure and lignin analysis. Sun and shade expanded leaves were also collected. Quantitative analysis of wood and leaf lignin was performed by the Klason method, and qualitative analysis by using Maüle and Wisner reagents. The presence of tyloses with lipidic compounds, vessels with appendices and a diffuse apotracheal parenchyma in the wood supported the species characterization. The occurrence of scalariform perforation plates with 20-40 bars, scalariform pitting, and fibre-tracheids indicate the primitive status of M. schottiana. The Mesomorphysm index suggests that this species grows on sites with no water deficit. M. schottiana leaves presented the following taxonomic characteristics: both short and long two-branched unicellular trichomes; a developed collenchymatous parenchyma; the arrangement and location of idioblasts with phenolic compound and large crystals. Sun leaves, exposed to higher light intensity, showed higher values for hypodermis layer; palisade parenchyma and spongy parenchyma; length and thickness of fiber-tracheids and stomata density. Histochemical tests revealed syringyl and guaiacyl units both in leaves and wood of M. schottiana. There was no difference in lignin content between sun and shade leaves. The high guaiacyl and syringyl contents support the species is rather woody.