POLLINA TION: HETEROSPOR Y. 



363 



ciently to strike against the stigma when the insect alights on the labellura. 

 In the mountains of North Carolina I have seen a beautiful little orchid, in 

 which, if one touches a certain part of the flower with a lead-pencil or other 

 suitable object, the poUinium is set free suddenly, turns a complete somer- 

 sault in the air, and lands with the di>k sticking to the pencil. Many of the 



Fig. 461. 

 Spray of leaves and flowers 

 of cytisus. 



orchids grown in conservatories can be used to demonstrate some of these 

 peculiar mechanisms. 



664. Pollination of the canna. — In the study of some of the marvellous 

 adaptations of flowers for cross pollination one is led to inquire if, after all, 

 plants are not intelligent beings, instead of mere automatons which respond 



Fig. 462. 

 Flower of cytisus grown in conservatory. 



Same flower scattering poller. 



to various sorts of stimuli. No plant has puzzled me so much in this respect 

 as the canna, and any one will be well repaid for a study of recently opened 

 flowers, even though it may be necessary to rise early in the morning to 

 unravel the mystery, before bees or the wind have irritated the labellum. 

 The canna flower is a bewildering maze of petals and petal-like members. 



