THE 



dicate plants of high rank, for the cat-tail flag (Fig. 221) 

 and many grasses have very compact inflorescences, and 

 they are supposed to be plants of low rank. It is to be 

 noted, however, that the very highest groups have settled 

 upon this as the best type of inflorescence. 



127. Summary. In tracing the evolution of flowers, 

 therefore, the following tendencies become evident : (1) 

 from naked flowers to those with distinct calyx and corolla ; 

 (2) from spiral arrangement and indefinite numbers to cyclic 

 arrangement and definite numbers ; (3) from hypogynous 

 to epigynous flowers ; (4) from apocarpous to syncarpous 

 pistils ; (5) from polypetalous to sympetalous corollas ; (6) 

 from actinomorphic or regular to zygomorphic or irregular 

 flowers ; (7) from loose to compact inflorescences. 



These various lines appear in all stages of advancement 

 in different flowers, so that it would be impossible to deter- 

 mine the relative rank in all cases. However, if a flower 

 is naked, spiral, with indefinite numbers, hypogynous, and 

 apocarpous, it would certainly rank very low. On the con- 

 trary, the flowers of the Compositae have calyx and corolla, 

 are cyclic, epigynous, syncarpous, sympetalous, often zygo- 

 morphic, and are in a remarkably compact inflorescence, 

 indicating the highest possible combination of characters. 



128. Flowers and insects. The adaptations between 

 flowers and insects, by which the former secure pollination 

 and the latter food, are endless. Many Angiosperm flowers, 

 especially those of the lower groups, are still anemophilous, 

 as are the Gymnosperms, but most of them, by the presence 

 of color, odor, and nectar, indicate an adaptation to the 

 visits of insects. This wonderful chapter in the history of 

 plants will be found discussed, with illustrations, in Plant 

 Relations, Chapter VII. 



