22 THE MORPHOLOGICAL DISTRIBUTION [CH. 



a bright red tint ; a variety of Cynometra cauliflora, bright rose-colour ; 

 Jonesia reclinata, golden-green to bright red; Brownea hybrida and 

 B. grandiceps, green spotted with red. Keeble further remarks that 

 the coloration of young foliage in low latitudes is of such general 

 occurrence that at the time of leaf-renewal, a tropiqal forest rivals in 

 its tints the autumnal forests of the temperate regions ; he also quotes 

 in confirmation the following extract from a paper by Johow (392), 

 writing of the Lesser Antilles: "...all at once a red tint, due to the 

 young foliage of the trees, appears in the landscape." Further details 

 of such cases are given by Stahl (62, 405), Ewart (406), Keeble (403), 

 Smith (420) and Weevers (421), and the physiological significance of 

 anthocyanin formation in young leaves is discussed in Chapter vm. 



3. The older leaves of many herbaceous plants often acquire a 

 considerable formation of anthocyanin by the end of the vegetative 

 (not necessarily autumnal) season (Lilium candidum, Digitalis purpurea). 

 Sometimes the whole plant becomes red in a striking way (Ckaerophyllum 

 sylvestre, C. temulum, Galium Aparine). 



4. The autumnal coloration characteristic of temperate climates 

 is one of the most pronounced cases of anthocyanin development. 

 With the onset of the cooler weather of autumn, anthocyanin appears 

 in quantity in the leaves of a number of trees, shrubs and climbing 

 plants (species of Acer, Rims, Euonymus, Crataegus, Viburnum, Cornus, 

 Vitis, Ampelopsis). In the Pflanzenleben, descriptions are given by 

 Kerner (398) of the beauty of the autumnal foliage in the forests along 

 the Rhine and the Danube, on the shores of the Canadian lakes of 

 North America and among the vegetation of the Alpine slopes. Kerner's 

 descriptions give such vivid pictures of autumnal colouring that this 

 opportunity is taken of quoting one of the passages from his account. 

 " The heights along the middle course of the Danube, for example, the 

 region known as the Wachan, below the town of Melk, shows wide 

 expanses of forest, in which beeches, hornbeams, evergreen oaks, common 

 and Norway maples, birches, wild cherries and pears, mountain ashes 

 and wild service-trees, aspens, limes, spruces, pines and firs take a share 

 in the greatest variety. Bushes of Barberry (Berber is vulgaris), Dogwood 

 (Cornus sanguined), Cornel (Cornus mas), Spindle Tree (Euonymus 

 Europceus and verrucosus), Dwarf cherry (Prunus Chamcecerasus), Sloe 

 (Primus spinosa), Juniper (Juniperus communis), and many other low 

 shrubs arise as undergrowth, and spring up on the margins of the forests. 

 The mountain slopes abutting on the valleys are planted with vines, 

 and near by grow peach and apricot trees in great abundance. In 



