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Summary

The relationship between bark internal structure and surface pattern remains in general unknown.

This is an investigation of the bark of 103 species of Malaysian Dipterocarpaceae. There is considerable variation between the species. Nevertheless it has been possible to induce general principles of bark construction.

The bark tissues are analysed into four components. These interact and produce various features of the surface. The components are: secondary phloem, laid down at the cambium; expansion tissue, developed mainly from the phloem rays; phloem proliferation tissue, developed from the parenchyma of the conducting phloem; and periderms. The secondary phloem does not vary; the other components do and their variation is described.

The bark components make up the living inner and the dead outer bark. The outer bark is acted on by external weathering processes and tangential strain to produce the fissures and ridges of the surface. The periderms and weathering processes control the sloughing of the bark and hence also its surface texture and colour.

The surface pattern of the bark is a visual summation of the surface configurations, the sloughing pattern, the texture and the colour. The slash appearance (oblique tangential section through the bark) is a visual summation of the inner and outer bark.

Barks are recognized in the forest from the subjective, unanalysed appearance of surface pattern and slash. These can now be analysed into objective constituent features themselves dependent on the bark tissues. This is summarized as Fig. 1.

Seven distinct Bark Types are described in Dipterocarpaceae (Table 1) with major differences in the structure and interactions of the components. The Bark Types can be placed in three groups with different amounts of expansion tissue.