THE FRUIT AND THE SEED 267 



3. Pollination by the Agency of the Wind. 



Ainong^ the plants whose flowers are pollinated b}^ the help 

 of the wind, the chief are the Grasses. The principal character- 

 istics by which such plants may be recognised are : — 



1. The flowers are inconspicuous, scentless and have no sugary 

 secretions. 



2. Their mithers hang out of the fioiver, so that the pollen 

 can be easily set free and carried away by the wind. 



3. The pollen is produced very abundantly to allow for 

 wastage. 



4. The pollen-grains are dry and small and, therefore, light. 



5. The stigmas are large and feathered, so that pollen-grains 

 floating in the air are easily caught. 



5. THE FRUIT AND THE SEED 



A, How fruits are formed. 



When the ovules are fertilized, the ovary begins to grow and 

 becomes the fruit, consisting of the pericarp and the seeds. If 

 the ovary is adnate to the receptacle, as in the Guava and the 

 Eose, the latter is also affected by the change and becomes a 

 part of the fruit cover. The same happens in the so-called 

 collective or multiple fruits (Mulberry, Jack, Fig, Ananas) that 

 consist of inflorescences of densely crowded flowers (or fruits) 

 on a common receptacle. Style and stigma usually take no part 

 in the changes caused by the fertilization of the ovules. They 

 fade and are dropped with the rest of the fading flower. In the 

 Poppy, as an exception, the sessile stigma remains on the top 

 of the ripe fruit. The calyx is often persistent. So in the Legu- 

 minosse, in the Myrtace^ and in the Labiat^e. In many of the 

 Composite the calyx forms the pappus, a flying apparatus, and 

 in Physalis an inflated cover over the juicy berry. 



1. The Pericarp. — The covering of the fruit (pericarp) is, 

 with the moditications mentioned above, formed of the carpellary 

 leaves. Three parts are distinguished in it. 



