AXKMOPIIILY 



321 



Fig. 198. 



Morning glory 



and dodder. 



which has lost its leaves, its ^reen color, and its firm stem 

 structure. The Broom-rapes {Orohanchaceae) likewise 

 have bract-like, chlorophyll-less leaves. 

 And so the saprophytic Indian Pipes {Mon- 

 otropaccae) show a similar reduction. 

 Somewhat allied to these modifications 

 are those in the case of the so-called In- 

 sectivorous plants where the leaves are modi- 

 fied into pitchers, or other structures for the 

 capture or digestion of insects. 



586. In their evolution from the primitive type of 

 flower to the more derived structures the Flowering 

 Plants have produced a multitude of forms of flowers 

 many of which show themselves extremely well-fitted for 

 certain very definite conditions. It is in connection 

 with the methods of pollination that the greatest varia- 

 tion is shown. It seems certain that the primitive flowers 

 were dependent, as are the vast majority of flower types 

 now, upon the aid of insects in pollination. However, 

 very numerous groups of Flowering Plants have given 

 up this so-caUed ''entomophilous" habit, and are polli- 

 nated by the wind (''anemophilous"). Such 

 flowers are usually marked by certain charac- 

 ters in common, viz. the abundance and 

 lightness of the pollen, the occurrence of the 

 staminate flowers in hanging clusters, "cat- 

 kins" (easily swung by the wind, as in the 

 Walnut, Oak, etc.) ; or with the branches or 

 inflorescence slender and swinging easily in 

 the wind (as in various grasses); the styles 

 and stigmas are usually very large, thus exposing more 

 surface on which the chance pollen grains may be caught; 

 usually too the pistils have but one, or very few ovules, 

 for each ovule requires a pollen grain for its fertilization 



21 



