POLLINATION 



131 



266. Some flowers have so developed as to prohibit self- 

 pollination. Very irregular flowers are usually of this cate- 

 gory. Regular flow- 

 ers usually depend 

 on dichogamy and 

 the selective power 

 of the pistil to in- 

 sure crossing. Flow- 

 ers which are very 

 irregular and pro- 

 vided with nectar and 

 strong per/unit are 

 usually pollinated by 

 insects. Gaudy col- 



207. Older flower of hollyhock. ors probably attract 



insects in many casts, but perfume appears to be a greater 

 attraction. The insect visits the flower for the nectar (for 

 the making of honey) and may unknowingly carry the 

 pollen. Spurs and sacs in the flower 

 are nectaries, but in spurless flowers 

 the nectar is usually secreted in the 

 bottom of tht flower-cup. Flowers 



which are polli- ^ 



aated by insects 

 are said to lie 

 entomophilous 

 1 " insect-loving" >. 

 Pig. 208 shows a 

 larkspur. Theen- 

 velopes are sepa- 

 rated in Fig. 209. 

 The long spin- at 

 once suggests in- 

 sert pollination. 



<v 



* 





206 Flower of tarl 





200 Envelop) irlsspur 



There are five Ide sepals, the 

 upper one being spurred, 

 There are four small p< 



The 



spur is ;i sepal. Two hollow petals 

 project into this spur, apparently Berving to guide the 



