VARIATIONS IN STRUCTURE 



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bilateral symmetry. This kind of symmetry of body is 

 very general among animals. A sweet pea is a familiar ex- 

 ample of an "irregular" flower; a vertical plane passing 

 through the center of it divides it into halves which are 

 alike. 



Fig. 108. — The water lily (Castalia odorata). Note the indefinite numbers of the 

 spirally-arranged petals and stamens. Note also the gradations of petals into 

 stamens. Note that the pistil has no style. 



The so-called irregular corollas, since they are really not 

 irregular at all, are better called zygomorphic (yoke-formed). 

 Similarly, regular corollas are called actinomorphic (ray- 

 formed) . 



D. Variations of the Androecium. — Usually the stamens 

 are all alike and separate. It is common to find two 

 whorls or sets of them. The anther is usually attached 

 to the filament at one end and stands in line with it. Some- 



