This section is from the book "A Text Book Of Materia Medica, Being An Account Of The More Important Crude Drugs Of Vegetable And Animal Origin", by Henry G. Greenish. Also available from Amazon: A Text Book of Materia Medica : Being an Account of the More Important Crude Drugs of Vegetable and Animal Origin.
Many species and varieties of Gossypium are cultivated in the United States, India, Egypt, etc. for the sake of the hairs that cover the seeds (see 'Cotton'); the most important are G. herbaceum, Linne, G. barbadense, Linne, and G. arboreum, Linne. The bark stripped from the root and dried constitutes the drug.
The bark occurs in thin, tough, fibrous strips to which long, thin, tapering rootlets are attached at intervals. The outer layer is a rough, cinnamon-brown cork which easily separates, exhibiting a paler cortex; the inner surface is whitish, silky and finely striated. The bast is laminated, the outer laminae exhibiting, when separated, surfaces bearing minute, brownish spots. No odour; taste somewhat acrid and astringent. The bark may be distinguished from the bark of D. Mezereum (see 'Mezereon Bark') by its rougher, darker surface and absence of leaf-scars or buds.
Cotton root bark yields a small amount of volatile oil containing probably furfuraldehyde and acetovanillone. It yields also about 10.6 per cent. of deep purplish resin. From an alcoholic extract of the bark, dihydroxybenzoic acid, salicylic acid, and two substances of phenolic nature, have been separated, together with betaine, a phytosterol, ceryl alcohol and fatty acids. No tannin is present (Power and Browning).