安徽大别山木本植物幼树小枝薄壁组织组成特征初探

Aims Axial parenchyma (AP) and ray parenchyma (RP) in secondary xylem have many important ecological functions, such as storage and translocation. Quantifying the compositions of parenchyma in secondary xylem will benefit the further research about their functions. However, the understanding of parenchyma compositions in current-year branches is still lacking. Methods Eighteen woody saplings in the Tianma National Nature Reserve were selected for sampling. The proportions of cross-sectional area occupied by AP and RP were measured. The variations in parenchyma among species and their phylogenetic signals were analyzed. Compared with the related dataset, the differences between twigs and trunks were tested. Important findings (1) The proportions of total parenchyma in twigs of the 18 woody saplings were 9.96%-18.56%, with the average of 14.80%; the proportions of RP (7.74%-15.45%) were higher than that of AP (1.13%-7.49%). (2) The total parenchyma (RAP) in twigs was lower than that in trunks, of which, RP in twigs was lower than that in trunks while AP showed an opposite pattern. The differences between twigs and trunks may be caused by the differences between different organs and different life history periods. (3) Significant phylogenetic signal was detected in the amount of AP in secondary xylem of twigs. This study primitively verified the phylogenetic signal of the secondary xylem parenchyma, and suggested that the difference between organs, and the difference between life history periods, had important effects on the variations of parenchyma.