458 THE SAPIXDALES 



type of flower so often noticed in the rose and preceding orders 

 has become reduced as a rule to the cyclic type and that five 

 numerous sets of organs are not of common occurrence. This 

 reduction of the flower and the suppression of parts is well 

 illustrated in the maples (Fig. 318). The sepals form a five- 

 lohcd calyx. The petals are often suppressed and a nectar disc 

 is developed outside the stamens, a distinguishing feature of the 

 order (Fig. 318, C}. The two whorls of stamens are suppressed 

 to a varying degree so that from four to eight commonly appear 

 and the pistils are normally reduced to two. More frequently the 

 flowers are imperfect, either the pistils or stamens of each 

 flower being aborted (Fig. 318, B). These two kinds of imper- 

 fect flowers are arranged on the same or different trees and t hey 

 are adapted to small short-tongued lapping insects which visit 

 these open types of flowers. The intelligent long-tongued bees 

 and butterflies generally avoid such flowers, having learned by 

 experience with colors and odors that a surer supply of food is 

 to be found in those flowers that conceal their nectar and so 

 exclude the promiscuous crowd of insects that swarm about the 

 simpler types. It should be stated that the development of 

 imperfect or incomplete flowers appearing in many of the orders 

 is not to be looked upon as a primitive condition, though common 

 in the lower monocotyledons and dicotyledons, since, throughout 

 the Angiospermae, forms will constantly appear in which one or 

 another set of organs fails to develop. The formation of wind 

 pollinated flowers, however, as in the box maple, is a return to a 

 primitive condition. 



The stimulation of fertilization results in a green wing-like 

 outgrowth on each of the ovaries that assists at first in the manu- 

 facture of food for the embryo and later becomes a dry, mem- 

 branous organ for seed distribution. This fruit, known as a 

 schizocarp or samara, is at first partly loosened from its support 

 and remains attached only by a small stalk (Fig. 319, B), which 

 requires a rather strong wind to snap it. Thus the fruit is 

 freed under conditions that will result in the widest dissemina- 

 tion of the seed. The development of the chlorophyll-bearing 

 tissue in immature fruits to assist in the work of food produc- 



