xvr POLLINATION AND FERTILISATION 215 



3. The flowers produce great quantities of pollen, which is 

 powdery and can easily be distributed by the wind. 



4. The versatile anthers are fixed on to slender filaments, 

 which hang out of the flowers so that a little wind can shake 

 them. (Fig. 212) The Nettle, for instance, can distribute its 

 pollen from the anthers by uncurling its filaments with a sudden 

 movement and scattering the pollen in a minute explosion. 



5. The stigmas are large and possess structures for holding 

 the pollen which comes in contact with them. (Fig. 212) 



Comparison 'of Insect-Pollinated and Wind-Pollin- 

 ated Plants. 



Insect- Pollinated. 



(1) The pollen is carried in a 

 definite direction, i.e., from flower 

 to flower. 



(2) Less pollen is produced, for 

 it is more certain of performing its 

 work. 



(3) The pollen is better pro- 

 tected from rain, dew, and 

 marauding insects. * 



(4) Less material is used in 

 producing pollen. 



(5) The maximum number of 

 seeds are produced with the mini- 

 mum amount of material. 



Wind- Pollinated. 



(1) The pollen is. carried in all 

 directions, and the great bulk of 

 it is lost. 



(2) Large quantities of pollen 

 are produced, most of which never 

 reaches the stigma of a flower. 



(3) The pollen is not so well 

 protected from the rain and dew. 



(4) Less material is used in pro- 

 ducing showy flowers and honey. 



(5) The maximum number of 

 seeds are produced with the maxi- 

 mum amount of material. 



Self-Pollinated Plants. By self-pollination is meant 

 where the pollen of a flower A pollinates the stigma of the same 

 flower A. There is a number of plants which produce flowers 

 that are always self-pollinated. Self-pollination is easily secured, 

 and seems in these flowers to give good results. The self- 

 pollinated plant is more likely to be pollinated than any other, 

 because the pollen is near at hand and only needs a little 

 movement to bring it on to the stigma. Either the wind or 

 insects may produce self-pollination, by distributing the pollen 

 from the anthers to the stigma. Several flowers, which are near 

 relations of the Daisy, have stigmas which curl downwards 

 until the pollen-ladened anthers are reached and self-pollination 

 takes place. The Poor-man's Weatherglass produces flowers 

 which may be cross-pollinated during the first three days after 

 opening. If not pollinated during this interval, the flowers 



