Ligament (phloem)

of a composite tissue with main infusion functions in the body of ferns, naked plants and
plants
. The ligament part of the bee plant consists of a sieve tube and companion cells, ligament fibers and thin wall cells of the ligament. The sieve tube is the basic component of the ligament, and the transportation of
organic
(sugar,
protein
, etc.) and certain mineral element ions is carried out by them. The ligament fiber is tough and has strong resistance to flexing. An ingredient that is mechanically supported in the ligament. Companion and sieve molecule originated in the same mother cell, and its exuberant physiological activity is related to the conduction function of sieve tube. The thin-walled cells of ligaments often contain crystallization and a variety of storage materials, which mainly play a storage role. Most ferns and naked plants have only sieve cells and thin-walled cells, no sieve tubes, companion cells, and typical ligament fibers. In the plant's primary structure, the ligament part comes from the original formation layer, and in the woody twin leaf plants and naked plants that have secondary growth, new ligaments and woody parts are formed continuously due to the activity of the tube formation layer in the roots and stems. Depending on the source, the ligament part from the original formation layer is called the primary ligament, and the ligament part from the vet formation layer is called the secondary ligament.