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This process is known as secondary growth; it is the result of cell division in the vascular cambium, a lateral meristem, and subsequent expansion of the new cells. These cells then go on to form thickened secondary cell walls, composed mainly of cellulose, hemicellulose and lignin. Where the differences between the seasons are distinct, e.g.
The term secondary raw material denotes waste material that has been recycled and injected back into use as productive material. Lumber has a high potential to be used as a secondary raw material at various stages, as listed below: Recovery of branches and leaves for use as fertilisers
Wood science [1] is the scientific field which predominantly studies and investigates elements associated with the formation, the physical and chemical composition, and the macro- and microstructure of wood as a bio-based and lignocellulosic material.
Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. [1] Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity and do not rot easily. Chemically, lignins are polymers made by cross-linking phenolic precursors. [2]
There are several databases relating to wood anatomy. One of them, InsideWood, is an online resource and database for wood anatomy, serving as a reference, research, and teaching tool. [13] [14] This database was created by several international researchers, members of the IAWA, mostly botanists, biologists and wood scientists. [15]
A section of rosemary stem, an example of a woody plant, showing a typical wood structure. A woody plant is a plant that produces wood as its structural tissue and thus has a hard stem. [1] In cold climates, woody plants further survive winter or dry season above ground, as opposed to herbaceous plants that die back to the ground until spring. [2]
An example of this is that secondary wall in wood contains polysaccharides called xylan, whereas the primary wall contains the polysaccharide xyloglucan. The cells fraction in secondary walls is also higher. [7] Pectins may also be absent from the secondary wall, and unlike primary walls, no structural proteins or enzymes have been identified. [4]
Collenchyma tissue is composed of elongated cells with irregularly thickened walls. They provide structural support, particularly in growing shoots and leaves (as seen, for example, the resilient strands in stalks of celery). Collenchyma cells are usually living, and have only a thick primary cell wall [6] made up of cellulose and pectin. Cell ...