THE FLOWER AND THE BEE 



ing in primitive groups of flowers to the exclusion of blue is 

 due to the strongly acid condition of the cell-sap. But in the 

 lily, pea, gentian, phlox, and mint families, which have highly 

 specialized and often irregular flowers, both red and blue 

 flowers are common. This second group of families are ad- 

 mittedly among the most recently developed in our flora, and 

 therefore we conclude that blue flowers are of later origin than 

 red and in many instances are derived from them. 



Trees with red flowers are rare, but shrubs are common. 

 Of trees, the peach, red buckeye, and red maple (Fig. 113) are 

 the best-known examples. Many red-flowered shrubs occur 

 in the rose, heath, and huckleberry families. The handsomest 

 American shrubs are undoubtedly the Rhododendrons, Kalmias, 

 and Azaleas, which exhibit a great variety of rose, pink, flame- 

 colored and red shades. It is rather remarkable that among 

 571 species of Composite there are only 9 red flowers. On the 

 other hand, 13 species, or one-half the mallow family, have 

 pink or red blossoms; and there are 22 species in the pink 

 family. In the buckwheat family the petals are wanting, but 

 the sepals are often red and sometimes the seed-vessels, stems, 

 and leaves. In the poppy family the flowers are crimson, 

 scarlet, or red, and the sap is also yellow and red. The most 

 brilliant red flower in our flora is the cardinal-flower (Lobelia 

 cardinalis, Fig. 112), which is pollinated by humming-birds. 

 There are also three flowers which are scarlet outside, but 

 yellow within, and rarely all over; they are the wild columbine, 

 trumpet-honeysuckle, and Maryland pinkroot, to all three of 

 which humming-birds are common visitors. 



Blue Flowers 



There are 325 blue flowers and 194 blue-purple flowers in 

 the flora of northeastern America. Blue is the highest color 



248 



