The Angiosperms 



171 



characteristic orders of no very close 'affinity, how- 

 ever, are often grouped under the head of Apetalae. 

 Some of these, both upon structural grounds and 



FIG. 18 



Types of Dicotyledonous Flowers. 

 A Pistillate flowers of Walnut. 

 B Staminate flower of Poplar. 

 C Section of apocarpous flower of Strawberry. 

 D Choripetalous flower of Spring-beauty (Claytonia). 

 E Sympetalous, zygomorphic flower of Cardinal flower 

 (Lobelia). 



from geological evidence, are evidently ancient 

 types, and there is no good reason to consider them 

 as reduced from petaloideous forms. Such, for ex- 

 ample, are the willows, poplars, oaks, and wal- 

 nuts. These all have diclinous flowers, and it is 

 difficult to say from what amphisporangiate forms 

 they could possibly have been derived. The flower 

 consists either of stamens or carpels, and the floral 



