Bark anatomy of radiata pine, corsican pine, and douglas fir grown in New Zealand

Abstract

The bark anatomy of Pinus radiata D. Don, P. nigra Arnold, and Pseudotsuga menziesii (Mirb.) Franco is described. Inner bark is composed of sieve cells, axial parenchyma, and rays. In P. menziesii it also contains fibres. In all species axial parenchyma is abundant. Some axial parenchyma cells have crystals which are more numerous in P. radiata and P. menziesii than in P. nigra. Horizontal resin canals are present but axial canals are absent. Outer bark or rhytidome is composed of alternating bands of periderm and dead phloem. Phelloderm is better developed in P. radiata and P. nigra than in P. menziesii. The boundary between phelloderm and the preceding phloem is poorly defined. Three types of phellem cell occur in P. nigra. Phellem in P. menziesii displays “growth zones”. Crystals are present in some phellem cells in P. nigra and P. menziesii. Dead phloem consists of cells which are distorted and crushed to varying degrees. Structural variability and the presence of dark-coloured polyphenols are two most striking features of bark. In each species, bark anatomy is distinctive. Anatomical differences between P. radiata, P. nigra, and P. menziesii are better defined in bark than in wood. Some physical properties of bark are explained in anatomical terms.