Influence of Leaf Activity on the Composition of the Wood Cell Wall

Abstract

NEARLY twenty years ago, Clarke¹ discovered a relationship between fibre wall composition, as revealed by botanical lignin reagents, and the variation in strength of home-grown ash (Fraxinus excelsior) timber. His subsequent observations on some three hundred other hardwoods demonstrated the wide application of this relationship and at the same time brought to light a marked difference between temperate and tropical species². The latter were found to be more resistant to compression along the grain but weaker in impact bending-strength than the temperate hardwoods on a weight-for-weight basis; they also showed a much stronger reaction with the traditional lignin reagents. Comparison of timber grown in the tropics with that of the same or closely allied species grown under temperate conditions indicated that the kind of lignin reaction must be related to a geographical or climatic factor and not to generic constitution.