Observations on the Formation of Protection Wood

Mature individuals of a number of coniferous and deciduous tree species (pines, oaks, elms, etc.) have in the central part of their stems a coloured heartwood core.This heartwood is impregnated with phenolic substances, and in deciduous tree species contains tyloses formations.In other tree species (spruces, beeches, maples, etc.), a visibly differentiated heartwood does not normally occur.This difference between wood of different tree species attracted early the attention of botanists, and led to attempts to classify trees accordingly into "heartwood" and "sapwood" species.Such a classitication seemed no doubt justified at the time, because the "heartwood" species, taken as a whole, are more resistant to fungus decay and deterioration than are the "sapwood" species.However, as we shall see, this grouping is an artifact, and can no longer be upheld.Botanical literature contains abundant records of the occurrence of "Pathological" (or "false") heartwood in tree species belonging to both of the above