CHAPTER Vll 



and assist in the most important of plant functions, the manufacture 

 of carbo-hydrates. Other functions of these colors are known, and 

 studies of the physiology of color in plants are developing truths that 

 should make us beware of interpreting color of flowers with reference 

 to insect visits solely. Still there seems to be no sufficient ground for 

 discarding the old theory that white and yellow flowers are best 

 adapted to the lower insects, white being of course also best for night 

 pollination, and that the various shades of blue and red appeal most to 

 guests of higher rank, bees having a decided preference for blue and 

 violet, and humming birds for red. Unquestionably white and yellow 

 are the most conspicuous colors against a green background, and as 

 recent investigations seem to indicate that the lower insects have 

 little sense of color, the greatest contrast must be most successful with 

 them. As a matter of fact, the color of by far the greater number of 

 flowers whose honey and pollen is accessible to short tongues, is 

 white or yellow. In some countries tables have been carefully pre- 

 pared with a view of discovering the relation between the colors of 

 flowers and the seasons. White is the prevailing color in spring- 

 time, before the visits of higher insects can be depended upon, yellow 

 coming next. Kerner suggests that pollen-loving insects choose 

 yellow flowers because yellow is the usual color of pollen. Although 

 we have no definite data in California, it will probably be generally 

 conceded that yellow is the prevailing tone of our early flora ; and 

 there is no doubt, in Southern California at least, that scarlet flowers 

 are most abundant during the summer months and that they have the 

 same habitat as humming birds. 



The theory that higher guests prefer blue and red, does not imply 

 that they never share with humbler guests the hospitality of white 

 and yellow flowers. Any one who watches the flowers and their 

 guests in the field, knows that butterflies flit along all brightly colored 

 flowers, though they usually choose to sip honey from deep recepta- 

 cles, which are probably more common in blue and red flowers. The 

 business-like bee clearly considers abundance of fare befo're color, and 

 humming birds are frequently seen sipping honey from flowers that 

 are not red. Still the experiments of Lubbock and others seem to 

 prove that, other conditions being equal, bees will always choose 

 blue ; and it is in harmony with this theory that many of our blue 

 flowers, the Brodiaea, many Gilias, some Phacelias, Salvias, sages, 

 Pentstemons and larkspurs, for instance, keep their honey accessible 

 to bees, but not to short-tongued guests, the theory being that these 

 flowers have become blue through the selection of the bees. That 

 hummingbirds choose scarlet, seems almost beyond question. The 



51 



