26 THE MOKPHOLOGICAL DISTRIBUTION [CH. 



petals in the Vienna gardens, e.g. Libanotis montana, had petals coloured 

 reddish- violet by anthocyanin on their under sides in the Alpine garden. 

 The glumes of all the Grasses which were green, or only just tinged with 

 violet at a low level became a dark brownish- violet in the Alpine garden. 

 The abundant formation of anthocyanin in the green tissue of the foliage- 

 leaves and sepals, and in the stem, was particularly apparent. The 

 leaves of the Stonecrops, Sedum acre, album, and sexangulare became 

 purple-red, those of Dracocephalum Ruyschianum and Leucanthemum 

 vulgare violet, those of Lychnis Viscaria and Satureja hortensis a brownish- 

 red, and the foliage-leaves of Bergenia crassifolia and PotentiUa Tiro- 

 liensis, even in August, had the scarlet-red colour which they usually 

 assume in sunny spots in the valley in late autumn." 



As regards Arctic vegetation, Gertz (19), on the authority of Wulff 

 (71), maintains that abundant production of anthocyanin is a dis- 

 tinguishing feature ; and so much so, that the periodicity of autumnal 

 coloration is very little marked. The causes of the intense colour in 

 Alpine and Arctic vegetation are dealt' with in Chapter vi. 



9. Production of anthocyanin in vegetative organs is characteristic 

 of certain halophytes (Salicornia, Suaeda, Atriplex). 



10. The red-leaved varieties of green-leaved types are due to the 

 production of anthocyanin, which is either absent from the type, or 

 present to only a slight extent (red-leaved varieties of Fagus, Berberis, 

 Brassica and Prunus). 



11. The petals and perianth are essentially the organs producing 

 anthocyanin. To these must be added the perianth-like calyx (Anemone, 

 Delphinium, Aconitum, Begonia and others). Also the bracts of the 

 inflorescence may develop anthocyanin to a large extent, and may either 

 assist (Salvia), or even take the place of, the corolla as organs of attrac- 

 tion (Bougainvillaea, Euphorbia, Poinsettia, spathes of Araceae). In 

 general, we may say that the stems and pedicels of most inflorescences 

 show an abundant formation of anthocyanin which no doubt increases 

 the conspicuousness of these parts ; yet, at the same time, the under- 

 lying cause is probably that the physiological conditions in all tissues 

 of reproductive organs enhance the formation of pigment. 



Anthocyanin is not confined to the perianth, but is frequently present 

 in the carpels and style : of its occurrence in the stigma we have many 

 examples among the Amentales (Myrica, Alnus, Betula, Corylus, Car- 

 pinus, Salix, Populus), as well as in Rumex and Ricinus. 



In the stamens, too, it is found, especially in many anemophilous 

 plants (Populus, Fraxinus) and in the Graminaceae (Molinia, Phleum, 



