The Formation of Heartwood and Its Extractives

Abstract

During evolution, trees developed several defense systems to maintain long term existence. One of these was the development of durable heartwood, now known to be due to the extractives present. The term “extractives” used in this chapter covers a large number of organic compounds of different classes which can be extracted from wood or bark with polar and non-polar solvents and which are the end-products of metabolism. As well as decay resistance, the extractives may confer color, insect resistance, lower fiber saturation point, and increased crush resistance of wood.1