AKGIOSPERMS 



339 



The flower. The flower in the angiosperms presents some new 

 and distinctive features which are common to both dicotyledons 

 and monocotyledons. The important advances made by the 

 flower, as compared with the strobilus of plants below the angio- 

 sperms, relate to the development of a showy perianth and of a 

 closed megasporophyll, or pistil, and to certain modifications in 

 the relation and number of sporophylls borne on the floral axis, 

 or receptacle. These new features can be most easily presented 



FIG. 200. Diagram designed to illustrate the corresponding parts of the spruce 

 strobili and the flower of the marsh marigold (Caltha palustris) 



a, flower of the marigold; 6, section of the flower; c, median long section of the 

 staminate strobilus of the spruce ; d, similar section of the ovulate strobilus 



by instituting a comparison between a simple flower like that 

 of the marsh marigold (Caliha palustris) and the strobili of 

 a gymnosperm like the spruce (Fig. 200). In the marigold 

 flower the perianth and the numerous stamens and pistils are 

 arranged in a spiral form on a dome-shaped receptacle like the 

 sporophylls on the axis of a spruce cone. Such flowers with 

 spirally arranged parts evidently correspond more nearly to the 

 strobilus of the plants below them than the cyclic flowers of the 

 mandrake and locust, in which the separate sets oL floral organs 

 are arranged in cycles on a flattened receptacle. If a median 

 longitudinal section of a marigold flower is compared with sim- 

 ilar sections of the male and female strobili of the spruce, the 



