. Biochemical systematics. Biochemical variation; Botany. OH HO. OH OH OH HO catechin gallocatechin The hydrolyzable tannins may occur as glycosides—the agly- cone often being a phenohc acid such as gallic acid. Brief but concise recent reviews of tannin chemistry are those of Mayer (1958) and Schmidt (1955), although these reviewers did not treat at all the sys- tematic distribution. As noted in an earlier section of this chapter Gibbs has studied the distribution of catechol tannins in the plant kingdom without, however, deriving systematic patterns of any great importance. Lignin: Lignin is
. Biochemical systematics. Biochemical variation; Botany. OH HO. OH OH OH HO catechin gallocatechin The hydrolyzable tannins may occur as glycosides—the agly- cone often being a phenohc acid such as gallic acid. Brief but concise recent reviews of tannin chemistry are those of Mayer (1958) and Schmidt (1955), although these reviewers did not treat at all the sys- tematic distribution. As noted in an earlier section of this chapter Gibbs has studied the distribution of catechol tannins in the plant kingdom without, however, deriving systematic patterns of any great importance. Lignin: Lignin is a plant product which potentially is of great systematic value, especially if technical advances occur which provide a method of analysing the sequential linkages of the building units and their cross hnkages. When Freudenberg (1959a) can raise even a rhetorical question such as whether lignin is a "molecular com- postheap" or consists of an orderly structure hke cellulose, one clearly recognizes the present Umitations of our knowledge of hgnin. Even the definition of lignin is based entirely on its degradation properties: "That plant component which, when refluxed with ethanol in the presence of catalytic amounts of hydrogen chloride, gives a mixture of ethanolysis products such as a-ethoxypropioguaiacone, vanillin, and vanilloyl methyl ketone from coniferous woods, and, in addition, the corresponding syringyl derivatives from deciduous ; (Brauns and Brauns, 1960). Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Alston, Ralph E; Turner, B. L. (Billie Lee), 1925-. Englewood Cliffs, N. J. , Prentice-Hall
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