Intraspecific variation of Paubrasilia echinata (Fabaceae) wood along a latitudinal gradient in Brazil

Abstract

Molecular and taxonomy approach have been made to understand the differences among the three morphotypes of Paubrasilia echinata, termed laranja, café and arruda. However, there is no wood anatomic study considering these morphotypes and their probable anatomical similarity. Considering as an endangered species with historical relevancy, it is crucial to recognize its wood anatomy to its conservation. This study aims to investigate the wood anatomy of P. echinata collected along its occurrence area (between 5°53′S 34°04′W and 22°56′S 42°30′W) and to examine the anatomical relationship among arruda, laranja and café morphotypes that was previously reported by molecular studies. The results indicate that the wood anatomy varied along its range of distribution a gradient of axial parenchyma and vessel features between the lower and higher latitudes was observed. Since arruda occurs in the collection sites of all four states studied, while café and laranja only in Bahia, the three morphotypes can be identified into of two groups based on wood anatomy: one formed by arruda samples and another by café and laranja, which differs from the previous molecular analysis. Combinations between higher percentage of axial parenchyma and wider vessels were observed in samples from RJ guarantying conductance and safety, while samples from RN and PB have smaller solitary vessels and scanty axial parenchyma, which could prevent embolisms. The present results do not support the categorization into subspecies or varieties. The findings also suggest that café and laranja share similar features than with arruda morphotype.