Wood
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The document discusses different types of wood. It defines wood as a hard, fibrous tissue found in tree stems and roots. Wood consists mainly of secondary xylem and may contain some primary xylem and pith. There are two main types of wood - sapwood and heartwood. Sapwood is lighter in color and contains living cells and food reserves, while heartwood is darker and contains substances like oils, gums, and resins. The document also describes different cell types found in wood, including fibers, tracheids, vessels, and parenchyma, as well as forms of cell wall thickening and structures like tyloses and annual rings.
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Wood
- 1. WOOD • Wood is a hard, fibrous structural tissue found in the stems and roots of trees and other woody plants. • It is defined as all that portion of the axis of woody plants lying inside the cambium line. • It consists mainly of secondary xylem, which may occasionally enclose in the center a very small amount of primary xylem and pith. • The wood is obtained from the trunks, branches or roots of the dicots or coniferous trees or shrubs.
- 2. Kinds of Wood I. Sapwood or Alburnum Sapwood usually occurs as whitish or pale in color, containing living cells and reserve food materials, i.e. starch. It is originally functioning both as conductive and as support. II. Heartwood or Duramen • This is usually dark colored, almost black, • it consists of dead cells where the food materials disappear, the parenchyma becomes more lignified. • filled with substances such as oils, gums, resins and tannin compounds. • the woods used in medicine are composed of heartwood.
- 3. • - The wood or xylem consists of: 1. - Fibers 2. - Tracheids 3. - Vessels 4. - Wood parenchyma 5. - Medullary rays
- 4. Forms of Thickenings 1.Annular: the thickening is in the form of rings at intervals along the inner surface of the cell-wall. 2.Spiral vessels: the walls show a spiral line of thickening. • The above mentioned two types of vessels are found only in the protoxylem. 3.Reticulate vessels: the thickening of the walls takes the form of a network.
- 5. 4. Pitted vessels: • the whole of the wall is thickened except of numerous small areas or pits which are usually bordered, which constitute the dominant kind of vessels present in commercial dicot woods. 5. Scalariform vessels: • the pits are sometimes transversely elongated and separated from each other by bar-like thickening, giving a ladder-like appearance.
- 8. Tyloses •Tyloses are balloon-like swellings, produced by the bulging of the cell-wall of the adjacent wood parenchyma or medullary ray cell, through the pit openings, into the cavity of the vessel. •Tyloses are usually devoid of contents occasionally starch granules, crystals, resin or gum may be present. •formation of tyloses may be induced in many plants by wounding and thus by pruning, tyloses are produced to block the cut vessels.
- 9. Annual Rings • Owing to the climatic variations, the vascular cambial tissue, in most woody plants, exhibits a periodical seasonal activity. • This result in the formation of alternate cylindrical layers of wood appearing in cross section as rings, each corresponding to one year growth, thus called annual rings.
- 10. Quassia Wood المـر الخشب • Botanical Origin Quassia is the dried wood of the trunk and branches of Picrasma excels (Sw.) Planch. (Jamaica Quassia) or of Quassia amara L. ( Surnam Quassia), Family Simaroubaceae.
- 11. Active Constituents 1- The bitter amaroids (0.75%): Quassin, Isoquassin and Neoquassin. • Quassin (of commerce) is a molecular complex of picrasmin, quassin and neoquassin. Uses 1- A non-astringent bitter tonic so can be used safely with iron preparation. 2- It is also used to destroy parasites, and given as enema, to expel thread worms. 3- Large quantities of Quassia are used in horticulture for the destruction of aphids. 4- Extracts known as "Quassin" are used to impact a bitter flavor to food and alcoholic products. 5- It may be safely used in all cases of lack of appetite such as anorexia nervosa. 6- Externally as lotion, it may be used against lice infestations.
- 12. • Special Chemical Tests Boil gently about 0.5 g of powdered Quassia + 5 ml of alcohol for few minutes filter add to the filtrate 2 drops of phloroglucin + 4 ml of conc. hydrochloric acid rose red color is produced within few minutes.
- 13. Sandal wood الصندل خشـب Botanical Origin: It is obtained from Santalum album L., Family: Santalaceae. Active Constituents: Volatile oil, the chief constituents of the oil is the alcohol Santalol. Uses: 1- A source of volatile oils. 2- The oil is a stimulant and disinfectant.