The cellular distribution of lignans in Tsuga heterophylla wood

Summary

Western hemlock heartwood contains patches of tracheids with large amounts of cellular inclusions. Microscopic and chemical examination of the wood showed several types of deposits containing the lignans matairesinol, hydroxymatairesinol and conidendrin. The deposits, which were often relatively pure individual lignans, frequently assumed different physical forms and chemical composition. A check in the wood contained three distinct forms of deposits each of which was a different lignan. Rays contained deposits physically similar to those in adjacent tracheids but, while lignans were present in the tracheids, they were not detected in the rays. Lignans lined tracheid walls as surface films and often encrusted the bordered pits. The amount of lignans in the wood was not related to wet wood zones although surface films and pit encrustations should have an influence on physical properties. The location and physical nature of lignan deposits in western hemlock heartwood indicates their biosynthesis has probably taken place at the heartwood periphery in the vicinity of the half-bordered pit.