298 EXPERIMENTS WITH PLANTS 



so that the color is visible from a distance (Elder, 

 Parsley family, etc.). The head of a Dandelion or 

 Sunflower is such a group, being made up of numer- 

 ous small flowers, and in the Sunflower there is an 

 interesting division of labor, in that the outer flowers 

 are for show only (producing no seed), while the 

 inner are inconspicuous but devote themselves entirely 

 to seed -bearing. It should be noted, morever, that 

 the contrast in color between the black center and the 

 yellow rim makes the flower much more conspicuous 

 than either color alone. Make an experiment on this 

 point by covering the center with the yellow petals 

 and then going off some distance to note the effect. 

 Look out for cases of color contrast, e. g., contrast 

 between the flowers and the background of leaves, 

 between the stamens and the petals, between the old 

 and fading flowers and the young ones, etc. 



Notice flowers which are growing beside a wall or 

 other screen which cuts off the light. Do they turn 

 toward the light? Does this aid in making them con- 

 spicuous ? Perform some experiments to test their 

 sensitiveness to the light. Study the behavior of Dan- 

 delion, Sunflower and Wild Mustard flowers, with 

 reference to "following the sun." 



It is said that not only are insects attracted by the 

 colors of flowers, but that they are partial to certain 

 colors. Bees are said to prefer blue and violet, to 

 care little for yellow, and to avoid scarlet. In my 



