Cambial Wounding

Abstract

Records of wound closure and wound treatment on trees date to ancient times (Bartlett 1935). Wound closure in trees not only intrigued early botanists, but it was also one of the methods they used to examine the origin of cambium. Lengthy quotes from some of these papers were included in the reviews of Trécul (1852, 1853b). For example, Duhamel in 1758 concluded that the wood of girdled stems was capable of producing new bark and this bark in turn produced new layers of wood. Meyen in 1839 wounded stems of Corylus, Salix, Syringa and Viburnum by removing strips of bark and covering the wounds with mastic. He noted “gelatinous-formed drops” exuding from the medullary rays on the wood surface. This liquid initiated “corticoïde” tissues, or false bark, but no new wood was formed. Dalbert in 1830 also removed patches of bark on stems of Fraxinus and covered them with glass plates sealed over the wound. He, too, observed drops of a gelatinous substance covering the bare wood surface. These drops multiplied and eventually gave rise to new bark similar to that described by Duhamel. Dutrochet, another contemporary, was not sure how the new bark formed after wounding. He suggested that it might arise from a metamorphosis of the “médulle centrale”, or pith. Although pith tissue does not extend to the secondary wood surface, he might have been referring to medullary ray tissue. Thus, the general view at this time was that a gelatinous sap exuded from the rays. According to Meyen, the sap was “a mucilage without organization”, although it presumably contained “the principle of ulterior organization”, as a tissue (Trécul 1853b). This mucilagenous sap was, of course, an early stage of callus formation.