THE WORK OF FLOWERS 295 



ing position on the approach of rain (Wood Anemone, 

 Scabious, Herb Robert, Potato, etc.) ; others accom- 

 plish the same result by closing the flower tightly, and 

 are useful as weather indicators (Poor Man's Weather- 

 glass, Water-lily, Dandelion, etc.). Such flowers are 

 regularly closed during the night, and thus the pollen 

 is protected from the dew. Many other flowers seem 

 to have no means of protection, but it will be found in 

 many cases on examination that the anthers them- 

 selves close to protect the pollen (Plantain, Grape, 

 Castor-bean, etc.), or a layer of hairs or a waxy 

 covering prevents the pollen from becoming wet. 



It should be noted that most of these devices pro- 

 tect the nectar, or honey, equally with the pollen. 



Flowers, as a rule, open and close quite regularly 

 at certain times of day: the great Swedish botanist, 

 Linnaeus, constructed a floral clock in which the hours 

 were told by the opening and closing of the flowers. 

 This naturally raises the question, Is the opening and 

 closing of the flower due to the action of light ? Select 

 some flowers which open and close quickly, such as 

 Oxalis, Dandelion, 1 etc., and try the effect of covering 

 them with a box in the middle of the day or of keep- 

 ing them under a dark box for two or three days, 

 during which time they should be examined at inter- 

 vals ; try to keep the temperature as nearly like that 



1 Some flowers never open a second time and consequently cannot be used 

 for the experiment. 



