CHAPTER II 



THE MORPHOLOGICAL DISTRIBUTION OF ANTHOCYANINS 



It is a striking fact that anthocyanins are almost universally distri- 

 buted. This is not fully realised until a systematic investigation is made, 

 and then- it is seen how few plants are entirely without these pigments. 

 Many plants may appear to the casual observer to be free from antho- 

 cyanin, but a closer examination generally reveals its presence, often 

 only in minute quantity, in such places as the base of the stem, the 

 petioles, bud-scales, bracts or even in some unexpected organ, as for 

 instance, the anthers and stigma. Again, an abnormal condition of 

 drought, or fungal attack, may cause its appearance when otherwise 

 the healthy plant is green. A number of plants, moreover, only form 

 anthocyanin in their young leaves at the beginning, or in their old 

 leaves at the close, of the vegetative season, or pigment may develop 

 shortly before the death of the whole plant. Reviewing the flowering 

 plants as a whole, two orders present an anomaly with respect to the 

 distribution of anthocyanin. The power to form anthocyanin seems 

 to be absent, first, from the Cucurbitaceae, as far as it has been possible 

 to ascertain, and secondly, from certain genera of the Amaryllidaceae 

 (Leuoojum, Galanthus, Ornithogalum and Narcissus). This observation 

 is confirmed by Gertz (19), who also adds to the list, Herniaria (Caryo- 

 phyllaceae) and Chrt/sosplenium (Saxifragaceae), some species of 

 Potamogeton, Eleocharis (Cyperaceae), Kniphqfia, Aloe, Reseda, i.e. R. 

 odorala and R. lutea, and Buxus. To the statement as regards R. odorata 

 and R. lutea exception must be taken, since both these species form 

 anthocyanin in their leaves under adverse conditions, such as are 

 brought about by drought or injury. 



The distribution of anthocyanin in the lower groups of plants has 

 been investigated by Gertz (19). It appears in the young fronds of 

 Osmunda regalis, of many species of Adiantum, of species of Doodia, 

 Pellaea and Davallia. Gertz also notes it in Blechnum and Azolla, 

 and among the Gymnosperms, in the cones of Picea, Pinus and Larix. 



w. P. 2 



