Wood (xylem)

of a composite tissue in viscera (ferns, naked plants and
plants)
. The wooden part of the bee plant (except for a few species) consists of catheters, tube cells, wood fibers, and thin-walled cells. The catheters and tube cells are the parts of the wood that have the function of infusion, and the transport of water and inorganic salt is achieved through them. Wood fibers are long-form cells that are strongly woody and have supporting functions. Wood thin-walled cells often contain starch and crystallization, and have storage function. Most ferns and naked plants have no catheters in the wooden part, nor typical wood fibers, and both the tube cells have the dual functions of conduction and support. In the plant's primary structure, the woody part comes from the original formation layer. In secondary growth of woody gemal leaves and bare-child plants, due to the roots and stems of the vein formation layer activities, there are constantly new wood and ligament parts formed. Depending on the source, the wood part from the original formation layer is called the primary wood part, and the wood part from the tube formation layer is called the secondary wood part. The secondary wood part is much more than the primary wood part and the secondary ligament part, so in the perennate wood stem, almost all the secondary wood parts are seen.