314 Field, Forest, and Wayside Flowers 



seldom receives and nourishes all comers. In one 

 peculiarity of structure the milkweeds are like the 

 orchids, that royal family of plants, for many or- 

 chids also send their pollen abroad massed into 

 two clusters, which are united by a disk. But each 

 orchid has its own very select and small circle of 

 guests, and some among them endeavor to please 

 one butterfly or moth friend, him and him alone. 

 They are, in evolutionary language, " highly spe- 

 cialized." 



On the other hand, a flower which keeps open 

 house to all comers is generally primitive in color 

 and structure. Such blossoms are apt to be yel- 

 low or white, with flat, open corollas, and without 

 spurs, honey-jars, or covering to protect the pollen. 

 So the milkweed is something of a problem to the 

 evolutionary botanist. 



And there is another puzzle for him in the in- 

 adequacy of Nature's very elaborate contrivances 

 to ensure the fertilization of the milkweed. Flowers 

 far simpler in structure and far less attractive to 

 insects bring a larger proportionate number of fruits 

 to perfection. 



The great blossom- clusters which crown the milk- 

 weed in July and August are made up of from 

 twenty-five to fifty flowers. But in September the 



