162 IvIVING PLANTS 



a dark red, the tulip tree a light 3^ellow, haw- 

 thorn and poison oak become violet, while the 

 sumacs and vines take on a flaming scarlet. 

 These colors exhibit some variation in accord 

 with the character of the soil on which the 

 plants stand. 



From the above it is to be seen that the 

 color of autumnal leaves is a screen under 

 cover of which the protoplasm retreats into 

 the main stem, carrying with it such other 

 substances as may be of use to the plant. 

 With the coming of spring the advance of 

 living matter in the form of leaves and shoots 

 is protected in the same manner by layers of 

 reddish violet, or reddish brown coloring mat- 

 ter, which disappears on the appearance of 

 the green coloring matter. 



It is of special interest to learn in this 

 connection that leaves which are covered with 

 a dense growth of silky, woolly or branching 

 hairs do not usually exhibit any marked au- 

 tumnal colors. The presence of the screen is 

 unnecessary in such instances because of the 

 protection afforded by the matted or felted 

 hairs on the surfaces. 



At a time previous to the beginning of the 

 withdrawal of the contents of the leaf, or the 

 formation of the autumnal colors, prepara- 

 tions had been steadily in progress for cutting 

 away the leaf when the proper time should 



