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 perfume are 

 usually pollinated by 

 insects. Gaudy col- 

 207. Older flower of hollyhock. ors 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. \^ 209. Envelopes of a larkspur. 

 Thp Inner snnr at V\ There are five wide sepals, the 



ine long spur at upper one being spurred . 



Once SUgJjests in- 208- ^ ower of larkspur. There are four small petals. 



sect pollination. The spur is a sepal. Two hollow petals 

 project into this spur, apparently serving to guide the 



