INTRODUCTION 43 



When the flower opens is a feature which has 

 given rise to much quaint folk-lore, and there are 

 weather plants which are used to tell the time of 

 the day. 



The protection of the flowers after they are open 

 is effected by bending over as in bell-like flowers, and 

 is connected with the preservation of the pollen or 

 honey from the rain or from insects. Some flowers 

 are always pendulous, but others are erect at first, 

 then drooping. Some sleep or close up during certain 

 parts of the day when it is wet, or at night. Others 

 close up to protect the flower from cold, as in the 

 Daisy. When the flower has been pollinated, and 

 the fruit is forming, a similar kind of movement 

 occurs as in the case of flowers that droop to protect 

 their honey or pollen. The petals of course also act 

 together with the calyx, as a protection to the inner 

 floral organs, the stamens and pistil. 



The adaptation of the perianth to the pollination of 

 the flower by insects, etc., is shown by the evolution 

 of the flower from possibly apetalous types at first, 

 through hypogynous types with distinct calyx, and 

 corolla (or either distinct), through those in which 

 the calyx is united or partly so (or with the corolla 

 united or partly so, or with both conditions), to those 

 in which the perianth is monosepalous or mono- 

 petalous or tubular. Whether this is the manner in 

 which the orders of plants have evolved is not abso- 

 lutely established, but this is the sequence in which, 

 theoretically, they may have done so in relation to the 



