A study on pit incrustation that seasonally occur in hardwood vessels

已知在某些硬木树种中，导管间纹孔被结壳物质堵塞。本研究旨在加深对这一现象的认识。对20科20属22种日本硬木树种的调查结果表明，仅在Yachidamo（Fraxinus mandshurica var. japonica：Oleaceae）。组织化学检查表明，结壳物质不是果胶和半纤维素等常见的多糖。它们在八桃树当年木质部中的沉积和消失过程在早材和晚材中存在差异。

It is known that intervessel pits are occluded by incrusting materials in some hardwood species. This study was carried out to deepen our understanding to this phenomenon. As a result of the survey of 22 Japanese hardwood species representing 20 genera from 20 families, the seasonal incrustation was noted only in Yachidamo (Fraxinus mandshurica var. japonica : Oleaceae). Histochemical examinations showed that the incrusting materials are not a common polysaccharide such as pectin and hemicellulose. The processes of their deposition and disappearance differed between earlywood and latewood in the current-year xylem of Yachidamo.