POLLINATION 



131 



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

 pollinatio)). 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. Floiv- 

 ers ivhich are very 

 irregular and pro- 

 vided with nectar and 

 strong perfume are 

 usually pollinated by 

 insects. Gaudy col- 

 oider flower of hoUyhock. qys probably attract 



insects in many cases, 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 the flower-cup. Flowers 

 which are polli- 

 nated by insects 

 are said to be 

 entomophilous 

 ("insect loving"). 

 Fig. 208 shows a 

 larkspur. The en- 

 velopes are sepa- 

 rated in Fig. 209. 

 The long spur at 

 once suggests in- 

 sect pollination. 

 project into this spur, apparently serving to guide th^ 



208. Flower of larkspur. 



The spur is a sepal 



19. Envelopes of a larkspur. 

 There are five wide sepals, the 

 upper one being spurred. 

 There are four small petals. 



Two hollow petals 



