STUDIES OF SEED-PLANTS 



209 



206. The Meaning of Flower-clusters. The value of 

 flower-clusters is believed to be threefold; namely, (1) to 

 attract insects which carry pollen, (2) to expose certain flowers 

 for pollination by wind, (3) to aid in distributionof seeds. 



FIG. 66. Types of flower-clusters. The positions of individual flowers are 

 represented by the black spots. The order of flowering is shown by the 

 numbers. A, raceme ; B, spike ; C, simple umbel ; D, head ; E, corymb ; 

 F, compound umbel ; G, cyme. Note that the first-formed flower is in 

 center of G, but at edge of clusters shown in C, D, E, F. 



With regard to insects, a cluster of small flowers held above 

 the leaves of the plant by the flower-stem appears to be in 

 a particularly advantageous position for attracting attention. 

 Certainly they are made more conspicuous to the human eye, 

 but the truth is that it is not yet certain whether most in- 

 sects which visit flowers are guided by the brilliant colors 

 of the flowers. It is well known that many inconspicuous 

 flowers are favorites of insects, which are probably led to the 

 flowers by odors more than by colors. However, many 

 botanists believe that conspicuous flowers do aid in attracting 



