Fibre pits in wood of Xylopia emarginata Mart. (Annonaceae), Reserva Biológica e Estação Ecológica de Mogi-Guaçu, São Paulo State, Brazil

(Fibre pits in wood of Xylopia emarginata Mart. (Annonaceae), Reserva Biológica e Estação Ecológica de MogiGuaçu, São Paulo State, Brazil). The influence of environmental conditions such as flooding areas on the anatomical features of wood is little known. The aim of this study was to compare the fibre pits in the stems and in the roots of Xylopia emarginata growing in a swampy forest and in a Brazilian savanna (Cerrado). Samples of stems and roots of X. emarginata were collected in the Mogi-Guaçu Biological Reserve and Experimental Station using a non-destructive method. Our anatomical study of the wood included analyses in two sectional planes (radial and tangential sections). Quantitative data of the fibre pits were processed using the Sample Size Estimator Worksheet software to obtain the statistical parameters, and BioEstat 2.0 was used to perform a non-parametric Mann-Whitney test. Analyses by scanning electron microscopy showed large differences in the number of fibre pits between stem and root in samples from the swampy forest and the Cerrado. The largest number of pits occurred in the radial walls of the fibres; there were at least twice as many pits in the roots as in the stems of specimens from both the swampy forest and the cerrado.