Bark

Broad concept refers to all
tissues
other than the formation layer of the stem (old trunk) and is the protective structure outside the trunk, i.e. the bark that can be peeled from the trunk during wood harvesting or processing and production. From the inside out, it includes the ligament, cortical layer and all dead tissue other than the ligament, cortical layer, and the accumulated peritaneous skin (see peri-skin) and the wood hydrant layer. To the final formation of the wood bolt formation layer as the boundary, can be divided into two parts of the structure: First, by the inner secondary ligament, containing more moisture, which has many living tissues, soft texture, called soft bark. Second, by the outside of the hard bark, that is, from the innerth layer of the wood hydrant layer to its outer layer of wood hydrant layer and wood hydrant layer outside the dead part, water content is very little, the texture is hard, mostly dead tissue, often strip or flaky off, so also known as the skin layer. The narrow concept of bark refers only to this part. The appearance of bark varies according to plant species and can be used as a identifying feature of tree classification: such as the pine's falling cortical layer is thick, overlapping scales, the surface cracks, the formation of deep ditches; The hard bark of hydrants and hydrants rarely falls off, and after the accumulation of wood hydrant tissue increases year by year, it can produce a very thick layer of wood hydrants, whose texture is soft, impermeable, non-conductive, non-thermal, and can resist the erosion of chemicals, and is widely used in industry.