THE COLORS OF NORTHERN FLOWERS. 691 



dreams." This supposed law is contradicted by tlie hjacintli, pausy, 

 Delphinium cardinale, and many other plants. Though red and 

 blue coloring never occurs among the roses, a hyacinth has been seen 

 to produce a perfectly pink and a perfectly blue blossom on the 

 same truss, and the Borraginacece afford examples of flowers turn- 

 ing from red to blue in even a short space of time. 



Blue is the highest color of the floral world, and is preferred by 

 bees. Blue flowers are, as a rule, highly specialized both in form 

 and color, and often possess marvelous mechanisms which aid in 

 disseminating the pollen. This coloring is very common in the mint 

 and pulse families, and in this district there are in the former forty- 

 nine and in the latter sixty-one species of blue flowers. Their struc- 

 ture is such that few insects besides the long-tongued bees can gain 

 access to the honey, and in some instances a single species of flower 

 is visited by a single kind of bee, as one of the larkspurs by one of 

 the bumblebees. While this high specialization of the flower may 

 insure intercrossing, it is yet open to many objections, such as scar- 

 city of proper guests, mechanical imperfections, perforation of the 

 flowers by bees, and development of the perianth at the expense of 

 the essential organs. 



It is noteworthy that when genera occur containing three or more 

 species they are seldom all blue or purple; one species at least, and 

 frequently more than one, is yellow, white, or red. In Trifolium, 

 T. pratense is rose-purple, T. repens white, and T. agrarium yellow. 

 In the genus Astragalus a part of the species are violet or blue and 

 a part white, and the same is true of Lespedeza and Vicia; in Lathy- 

 rus three species are blue-purple, one yellow, and one yellowish 

 white. It is probably more advantageous in these genera for a part 

 of the species to be of one color and a part of another than for all 

 to be blue. "When species are closely allied bees tend to visit them 

 indiscriminately, as has been observed to be true of the buttercups, 

 Spirceas, and golden-rods. During an afternoon the writer care- 

 fully collected the insect visitors to Solidago hicolor, our only cream- 

 colored golden-rod. Both the number of species and of individuals 

 taken was much larger than upon the yellow-flowered and more 

 abundant varieties of this genus growing near by. There could be 

 no doubt that the whitish coloration was beneficial in enabling in- 

 sects to distinguish it more readily. Many purplish flowers are 

 regular, often showing indications of degeneration, are devoid of 

 honey, and are self-fertilized or adapted to Diptera, or, as in He- 

 patica, which is visited by bees for the pollen, open to a wide circle 

 of visitors. In the sea purslane {Sesuvium maritimum), a pros- 

 trate maritime herb, there are no petals, but the five-parted calyx 

 is purplish inside. The genus Ammannia of the Lytliraceos has the 



