PHANBROOAMIA. <iQQ 



hibiting several divergent groups, the one containing the 

 Asterald Cohort rising highest. In such an arrangement 

 the orders of the Apetalse would be placed as degraded or 

 simplified offshoots mainly from the Choripetalse, while a 

 few would doubtless be regarded as directly lower than 

 and preceding the latter group. 



537. A great many Dicotyledons show adaptations for 

 pollination by insect 

 agency, and it is safe to 

 say that more than half 

 the species are more or 

 less dependent upon the 

 visits of insects in order 

 that their ovules may be 

 fertilized. In a general 

 way it may be said that 

 the showy flowers with 



a bright calyx or COrol- Fiq. 144.-Tlie Cherry (Piunuscerasus), with 

 1 1 .r IT i J clustered flowers. 



la, or both, are pollinated 



by insects, while those without showiness are wind-polli- 

 nated, or close-fertilized. The plants of the Apetalous 

 orders are for the most part not visited by insects; few of 

 them have bright colors, and few produce nectar. 



538. The simpler Choripetalse, as the Crowfoots (Fig. 

 143) and their near allies, attract insects by their showy 

 perianth, and the nectar they secrete. Cross-fertilization 

 is generally secured by a difference in the time of maturity 

 of stamens and pistils (i.e., by dichogamy), apparently, 

 however, often permitting close fertilization. The same 

 IS true in general of most of the regular flowered Chori- 

 petalse. Thus in the Roseworts (Fig. 144), while nectar is 

 usually abundant and tbe flowers are generally sweet- 



