18 THE MORPHOLOGICAL DISTRIBUTION [CH. 



As regards the Augiosperms, the present chapter contains an enu- 

 meration of the organs in which anthocyanin is formed in the varying 

 circumstances of plant life. Some authors have attempted to classify 

 the appearance of anthocyanin into permanent and transitory or 

 periodical, normal and abnormal, etc., etc., but the variety and com- 

 plexity of the underlying physiological causes in each case render 

 such classifications of little value. No distinctions of this kind are 

 attempted in the following classification. 



1. The leaves of the majority of plants are green; nevertheless, 

 in many genera and species, anthocyanin is always present as a normal 

 development, and a complete series might be found ranging from plants 

 whose leaves show a faint trace of anthocyanin to those whose leaves 

 are more or less heavily pigmented. Some writers, notably Kerner 

 (398), have pointed out that plants in which there is a considerable 

 development of anthocyanin have often a special habitat. It would 

 seem on the whole that this view is justified, though in many instances 

 red pigmentation appears to be a specific character bearing no special 

 relation to environment, as for example in Geranium Robertianum. 



Kerner's views can be best expressed in his own words: "...antho- 

 cyanin frequently occurs only on the under side of foliage-leaves. 

 This is observed especially among plants in the depths of shady forests, 

 which, although belonging to widely-differing families, agree in a remark- 

 able manner in this one point. One group of these plants has thick, 

 almost leathery, evergreen leaves lying on the ground, which arise from 

 subterranean tubers, or root-stocks, or from procumbent stems. The 

 widely-distributed Cyclamen europ&um may serve as a type of this 

 group. . . .Amongst other species belonging to this group may be mentioned 

 Cyclamen repandum and C. hederifolium, Cardamine trifolia, Soldanella 

 montana, Hepatica triloba and Saxifraga Geum and cuneifolia. Growing 

 in habitats similar to these are to be met biennial, occasionally perennial, 

 plants which in autumn form a rosette of leaves on their erect stems 

 which survive the winter ; these are always coloured violet on the side 

 turned towards the ground, while the leaves which develop in the 

 following warm summer on the elongated flower-stalks usually appear 

 green below. To this group belong, especially, numerous Cruciferae 

 (e.g. Peltaria alliacea, Turritis glabra, Arabis brassicceformis) ; species 

 of spurge (e.g. Euphorbia amj/gdaloides), bell-flowers (e.g. Campanula 

 persicifolia), and hawkweeds (e.g. Hieracium tenuifolium). Finally, 

 deciduous shrubs are to be found in the depths and on the margins of 

 forests whose leaves do not survive the winter, but which produce 



