CHAP. XX INCOMPLETE, IRREGULAR FLOWERS 91 



plants. Which is most thoroughly cross-pollination ? 

 Why? 



7. The student should make a special note of the fact that 



imperfect flowers are constructed so as to prevent 

 close-pollination and compel cross-pollination. 



8. Is the cross-pollination in the Begonia effected by the 



agency of the wind or of insects ? Why ? 



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II. Incomplete Flowers. An imperfect flower is neces- 

 sarily also incomplete, since it lacks entirely one of the four 

 circles. But a perfect flower may also be incomplete ; for 

 example, take the flower of an Anemone, Hepatica, or 

 Prince's Feather, and notice : 



1. That both stamens and pistils are present. 



2. That only one circle of floral leaves is present, and when 



only one is present, it is called the calyx, without 

 regard to its coloration. 



III. Irregular Flowers. Take the flowers of a Pea, 

 Bean, Wistaria, Locust, or some other leguminous plant, and 

 examine the corolla carefully. Notice : 



1. The upper broad petal of a different shape (and perhaps 



of a different color) from the rest. It is called the 

 standard or banner, and is spread out to attract the 

 insects. 



2. The tivo side petals, called the wings, upon which the 



insects alight. 



3. The two lower petals, cohering more or less at their tips 



(but seldom really grown together), forming the keel, 

 enclosing the stamens and pistil. . 



4. Remove these five petals, lay them down in order, and 



sketch each to show relative size and shape. 



