Angiosperm wood tissue

In Gymnosperms the secondary xylem (wood) tissue of roots, stems and leaves consists either of punctated or scalariform cells, whereas in Angiosperms the secondary wood tissue may be varied in structural aspect. 

Figure 1. Commercial timber is obtained from angiosperms (hardwoods) or from gymnosperms (softwoods). The wood tissue is made up largely of dead, hollow plant cells that are arranged to form a composite material of substantial void volume.

The flavonols reported in woody tissues are listed in Table 7.5.2. Some typical structures are 16 through 23. The most common flavonol of higher plants is quercetin and this substance is reported as a very frequent constituent of gymno-sperm woods and barks. In the angiosperm woods, the flavonols most frequently... 

WOOD. A vascular tissue which occurs in all higher plants The most important commercial sources of wood are the gymnosperms, or softwood trees and the dicotyledonous angiosperms, or hardwood trees. Botanically, wood serves the plant as supporting and conducting tissue, and it also contains certain cells which serve in the storage of food. The trunks and branches of trees and shrubs are composed of wood, except for the very narrow cylinder of pith in the center and the bark which covers the outside. Botanists refer to wood by its Greek name, xylem. 

Wood is found mainly in trees and shrubs, although woody tissues are also found in some herbaceous plants. Wood is a complex material and living tree trunks are composed of a variety of tissues (pith, xylem, cambium, phloem, and bark). The wood from most angiosperm trees is known as hardwood, while the wood from gymnosperms is known as softwood. 

Wareing PF, Hanney CEA, Digby J (1964) The role of endogenous hormones in cambial activity and xylem differentiation. In Zimmermann MH (ed) The formation of wood in forest trees. Academic Press, London New York, pp 323-344 Wetmore RH, Rier JP (1963) Experimental induction of vascular tissues in callus of angiosperms. Am J Bot 50 418-430... 

Wood (xylem) is a vascular tissue which occurs universally in gymnosperms (soft wood trees) and dicotyledonous angiosperms (hard wood trees). The wood consists of lignin and holocellulose. The former is a polymer consisting of repeat phenolpropane units and the latter consists of cellulose and hemicellulose. Hemicellulose is a mixture of pentosans, hexosans and polyuronides. 

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