THE FLOWER AND THE BEE 



less yellow flowers in the ancient flora, and the advantage 

 afforded by greater conspicuousness would soon cause them to 

 become common. 



Among the flowers which owe their yellow color chiefly to 

 carrotin are the Ahutilon, Adonis, squash, Forsythia, sunflower, 

 jewelweed {Impatiens biflora), Kerria jajponica, evening-prim- 

 rose, yellow roses, dandelion, and nasturtium. The yellow pig- 

 ment xanthophyll does not occur in plastids, but is dissolved 

 in the cell -sap. To it are due the yellow color of the peel of the 

 lemon, the yellow flowers of the dahlia, butter-and-eggs (Linaria 

 vulgaris), snapdragon, and all the yellow-flowering thistles as 

 well as many other flowers. (Fig. 107.) 



There are 790 yellow flowers in northeastern America, which 

 vary in size from the large campanulate cups of the squash to 

 the small flowers of the creeping buttercup. Usually they are 

 wheel-shaped, as in the buttercups and fivefingers; but not 

 infrequently they are very irregular in form, as in the pea and 

 figwort families, where the corolla bears a more or less fancied 

 resemblance to a butterfly or the head of a reptile. As a 

 whole, however, they are much less specialized than red and 

 blue flowers. Irregular yellow flowers probably owe their hue 

 largely to the great persistency of the yellow pigment carrotin. 

 Both yellow and w^hite flowers pre common in primitive families. 

 For instance, in the buttercup family there are 38 yellow and 

 26 white flowers; in the mustard family, 46 yellow and 54 white; 

 in the rose family, 39 yellow and 35 white. 



While trees and shrubs with white flowers abound every- 

 where, trees and shrubs with yellow flowers are comparatively 

 rare. A number of common trees have small yellowish or 

 greenish -yellow flowers, as the rock-maple, striped maple, chest- 

 nut, and basswood; while among shrubs there are the barberry, 

 fly-honeysuckle, jessamine, and bush-honeysuckle. Familiar 



232 



