18.1 I ntroduction 18.2 Physiology of flavonoid accumulation in plants J. B. Harborne et al. (eds.), The Flavonoids © Springer Science+Business Media Dordrecht 1975 Many reports detail the accumulation of 'anthocyanin' without identifying the pigment or mixture of pigments. Increased accumulation is assumed. Decreases attributable to light are designated by (decr), trace amounts by (tr). 2 Abbreviations as follows: Hl = High Intensity responses to either blue (B), green (G), red (R) or far red (FR) light of 1 J cm -2 or moretotal irradiation. Prr = low energy red, far-red reversible photoresponse. UV = ultraviolet light.