22 



hues than before, such as the Oaks, Maples, Poplars, Sassa- 

 fras, Yaccinium, Prunus, Viburnum, Rubus, Ampelopsis, 

 Amelanchier, Leucothoe, Clethra, Vitis, Salix, etc. A few 

 of the preceding are purplish in spring and yellow in fall. 



As tending to strengthen the view that spring colors are 

 screen colors, is the fact that many plants display these 

 colors only in the sun, but in the shade they are entirely 

 green, as Vaccinium vacillans and V. Pennsylvanicum 

 (blueberry). 



In addition to these spring colors, the leaves of numerous 

 species of a semi-evergreen character which have weathered 

 the winter months, but changed to brighter hues where 

 exposed to the sun, still linger on their stems, as Black- 

 berry, Rumex, Strawberry, Cranberry. Boxberry (Gaul- 

 theria), Smilax, Chimaphila, Pyrola, Mahonia, Lonicera, 

 Kalmia augustifolia, etc. Among them all it is possible, if 

 one will take the pains, to obtain a bouquet of different 

 colored leaves vying in beauty with those of autumn. 



The change of color, especially to yellow, usually begins 

 at the peripher}^ of the leaf and then follows the chlorophyll 

 as it recedes, and its nitrogenous elements are absorbed into 

 other parts of the plant. But this manner is not uniform ; 

 maples often show the red color first in the veins, and some 

 while green, and others when changed to yellow, are not 

 infrequently blotched and variously splashed with blood-red. 



Circidiphyllum frequently ])egins to develop its pure 

 yellow at the base of the leaf. Leaves suffering from in- 

 sects are apt to change color first at the affected part ; those 

 developing scarlet, crimson, purple brown, etc., often have 

 those hues confined to the parts only which are reached by 

 the direct rays of the sun, while the shaded })ortion of the 

 leaf remains green or yellow, and the outline of the upper 

 or shading leaf is depicted as a sun picture upon the lower 

 one. Examples of the latter are common in Maples, Ampe- 

 lopsis Veitchei, Gaultheria (boxberry), Vaccinium corym- 

 bosum (blueberrj' ), Lonicera, etc., and are especially notice- 



