CHAP, xvin A TYPICAL OR PATTERN FLOWER 85 



VIII. Ground Plan of the Flower. Draw by the aid of 

 a pair of compasses four faint concentric circles, one within 

 the other. 



1. Upon the innermost, represent the five pistils (drawing 



cross-sections of the ovaries) . 



2. In the next outer circle, represent the stamens (by cross- 



sections of the anthers) alternating with the pistils. 



3. In the next outer circle, represent the petals (by cross- 



sections) alternating with the stamens, and finally 



4. Represent the sepals in the same way in the outermost 



circle. 



5. This is what is usually called a ground plan of the flower 



and represents the number and alternation (or lack 

 of it) of the parts in such a way that they may be seen 

 at a glance. To be especially accurate, the particular 

 way, which varies somewhat in different flowers, in 

 which the sepals or petals overlap one another, should 

 also be represented. 



IX. The Numerical Plan of the Flower. The numerical 

 plan of a flower is represented by the number which pre- 

 dominates in the different circles of the flower. In the 

 flower just studied the same number is represented in each 

 of the four circles. What is its numerical plan ? 



X. The Crassula is a type or pattern flower because it is 

 complete, regular, and symmetrical, has alternation of parts, 

 and all the parts free and distinct one from the other. A 

 flower must have these five qualities to be a pattern flower. 

 Few flowers are pattern flowers. 



XI. A flower must contain either pistils or stamens (or 

 both). Some flowers are reduced to a single stamen or a 



