262 FREAKS OF PLANT LIFE. 



Although light and temperature appear to have an 

 influence on the opening and closing of flowers, yet 

 in some species at least, which open or close near a 

 definite time, there is a decided effort made to open 

 or close when the appointed hour arrives, even when 

 the external conditions are unfavourable. De Can- 

 dolle made some experiments with flowers excluded 

 from the daylight, and found that in some cases a 

 plant which was accustomed to flower in daylight at 

 a certain time, still followed the clock hour in their 

 opening and closing. 



Fritsch made some extensive observations at 

 Prague on the opening and closing of flowers.^ He 

 was of opinion that there is no hour of the day when 

 the flowers of some plant do not open, and in the 

 majority of instances they are closed at sunset. 

 With the exception of a few hours near midnight, 

 there is no hour at which blossoms do not begin to 

 close — the maximum about six o'clock in the even- 

 ing. In a few plants the complete expansion lasts 

 only an hour, sometimes not so much. In those 

 blossoms which are fully expanded in the morning 

 the duration of expansion is short. In those blossoms 

 which expand in the afternoon, the condition of 

 waking is limited by the length of time the sun is 



^ See " Journal of Horticultural Society of London," vol. viii.,. 

 p. 1. 



