CHAPTER 20 • REPRODUCTION IN FLOWERING PLANTS 



1 Can flowering plants reproduce in any other way than by seeds? 



2 Can any plants produce seeds without flowers? 



3 How does pollen act in a flower? 



4 Are the eggs of all flowering plants fertilized inside the flower? 



5 Is there anything in animals to correspond to seeds? 



6 Is there anything in plants to correspond to the egg of a bird? 



7 Do any animals depend upon other species in reproduction, as 



flowering plants depend upon insects? 



8 Is there anything in animals to correspond to pollen? 



By far the most varied in the number of species, and certainly the most 

 complex, are the flowering, or seed-bearing, plants. Some of them live but a 

 few weeks of summer weather; others grow to be hundreds of years old. And 

 they have spread all over the habitable earth. These plants are typically sta- 

 tionary, firmly rooted in the soil, in contrast to land animals, which move 

 about freely. Yet they manage to bring about sexual reproduction between 

 individuals far apart, and to spread their offspring out in all directions ahead 

 of the free-moving animals. They manage to capture various natural move- 

 ments that go on about them, both animate and inanimate, just as they have 

 captured the energy of sunlight through their chlorophyl. 



In their formation of gametes, and especially in the mechanism by which 

 two gametes are brought together, the flowering plants present an amazing 

 and fascinating variety of forms and structures. 



In What Ways Are All Flowers Alike? 



The General Idea of a Flower^ Almost anything on a green plant that 

 is not green catches the attention. There are many leaves and other growths 

 that arrest the eye; but a flower is a highly speciaUzed structure. Flowers 

 range in size from an eighth of an inch or less across to perhaps a yard or more. 

 They dirfer also in shape and relative numbers of parts, as well as in colors. 

 And they difl"er in their arrangement — in relation to the leaves and in relation 

 to one another on the stems of a plant (see illustrations, pp. 12 and 31). 



The essential organs in all flowers are those that have to do with producing 

 seeds. The seeds originate from tiny structures called ovules, or "little eggs", 

 which are borne in special organs at the center of the flower, called carpels — 

 from a Greek name for fruit, J^arpos. 



The single carpel of a flower, or the structure formed by the carpels fused 

 together, is sometimes called a pistil, from the fancied resemblance to the 



iSeeNo. I, p. 414. 

 398 



