梣属11种植物次生木质部附物纹孔的电镜观测

SEM Observations and Measurements on Vestured Pits of Secondary Xylem in 11 Species of Genus Fraxinus

应用扫描电镜对梣属11种植物次生木质部导管附物纹孔的分布和形态进行了详细的观察,应用Carnoy2.0软件和扫描电子显微镜采集的照片,测定了附物纹孔丰富度指标和纹孔数量特征指标。电镜观察表明,梣属11种研究植物次生木质部导管分子侧壁附物纹孔的分布和形态变化较大,附物纹孔丰富度指标的统计描述进一步证实附物纹孔的分布变化大;3个附物纹孔丰富度指标分别与管间具缘纹孔数量特征指标的逐步回归分析表明,导管侧壁附物纹孔丰富度2个指标,即导管外纹孔口附物频率与导管纹孔腔附物频率随纹孔口面积百分比的增大而增大,推测梣属植物附物纹孔丰富度与纹孔几何构造及数量特征有关。研究认为,附物纹孔在梣属植物稳定存在,是可界定梣属植物的木材解剖性状。

The distribution and micromorphology of vestured pits in secondary xylem of eleven species re- presenting genus Fraxinus were investigated in details by means of SEM. Richness indexes of intervascular vestured pits and quantitative features of the bordered pits were measured on SEM images using software Carnoy 2.0. Scanning electron microscopy illustrates that vestured pits in the vessel elements of secondary xylem of studied species varied considerably in distribution and micromorphology,and the statistic descrip- tion of richness indexes further confirmed the great variable distribution of vestured pits. Stepwise regres- sion analysis between respective richness indexes and quantitative features of the bordered pits indicated that 2 out of 3 richness indexes including frequency of vestured vessel outer aperature and frequency of ves- tured vessel pit chamber increased significantly with increasing Fap （aperture fraction）, suggesting that richness of vestured pits was correlated with geometric structure of the bordered pits. It can be inferred that consistent occurrence of vestured pits in genus Fraxinus from the common presence of the vestured pits in studied species. Therefore,the occurrence of vestured pits can delimit the genus Fraxinus.