THE FLOWER AND THE BEE 



The largest tree-flowers known belong to the Magnolia. 

 One Southern species has a white flower, with a purple centre, 

 which measures ten inches across. "Their effect in early spring 

 is grand beyond description, illuminating the whole landscape 

 and filling the air with rich perfume." Of the five northern 

 species four are white, and one is greenish yellow. Magnificent 

 white flowers are likewise displayed by several species of pond- 

 lilies; but very frequently white flowers are of small size, and 

 conspicuousness is gained by their aggregation in masses. 



Small, densely clustered white flowers standing in the same 

 horizontal plane and affording a convenient landing-place for 

 insects are very common in the mustard, saxifrage, carrot, 

 honeysuckle, and aster families. This type of flower-cluster 

 is excellently illustrated by the carrot family, or Umhelliferoe, 

 (Fig. 110.) To this family belong the caraway and carrot, the 

 wild parsnip, the water-hemlock, and the water -parsley, plants 

 growing luxuriantly by the roadside, along the river, and in the 

 meadow. The flowers differ very little in structure, and the 

 species can be separated only by the aid of the mature fruit. 

 Insects of every kind are welcome, and no other family of 

 flowers has so large a number and variety of visitors. The 

 nectar is fully exposed, and self-fertilization is prevented by 

 the anthers and stigmas maturing at different times. In the 

 Compositce 126 species have either the ray or disk florets white. 

 (Fig. 111.) In bicolored heads, or capitula, where the rays are 

 white and the disk flowers yellow, tliere can be no doubt that 

 the white rays are derived from yellow-colored ancestors. In 

 crownbeard (Verbesina) all of the 5 species have yellow disks, 

 but 1 has white and 4 yellow rays. In the genera everlasting 

 (Antennaria) and cudweed (Gnaphalium) the yellowish-white 

 flowers have retrograded and lost their original yellow hue. 



In the orchis, pea, mint, and figwort families there occur 



242 



