MOVEMENTS AND ATTITUDES OF PLANTS 153 



are equally interesting and easy to observe. Sleep- 

 movements are common and, in different species, occur 

 at different times of the day and night. Usually flowers 

 pollinated by day-flying insects are open by day and closed 

 at night, while flowers visited by night-flying moths are 

 open in the evening or at night, when they are often sweet- 

 scented, and are white or pale yellow in colour. Some 

 plants owe their common names to their habit of opening 



Fig. 100. Evening Primrose, showing the Movements of the 

 Parts as the Flower opens. 



and closing their flowers, e.g. the Daisy (day's-eye), John- 

 go-to-bed-at-noon, and Poor Man's Weather-glass. These 

 movements are related either to the habits of the insect- 

 pollinators, or to weather-changes, many flowers closing 

 during cold, dull, or wet weather, and so protect their honey 

 and pollen. 



The opening of some flower-buds occurs so quickly as 

 to be easily observable. It is quite exciting to watch the 



