MOVEMENTS AND ATTITUDES OF PLANTS 155 



The movements of the flowers and flower-stalks of 

 Poppies, Columbines, and Bellflowers {Campanula) should 

 be compared and their differences noted. 



In some cases the whole inflorescence is involved in the 

 movements, e. g. in the Dandelion it is erect in bud, and 

 when the flowers are open (Fig. 104) ; at night and in wet 

 weather the flowers close and are protected by the inner 

 whorl of bracts. After pollination the stalk grows, bends 

 over and lies almost prostrate, becoming erect again as the 

 fruits ripen. At this stage the disk enlarges and becomes 

 convex, the bracts turn backwards against the stalk, the 

 pappus-hairs spread outwards and the fruits are ready for 

 dispersal by the wind. In the Coltsfoot the stalk is erect 

 in the bud and in the flowering stages. After pollination 

 the upper part bends over, bringing the head into a drooping 

 position, and the fruits, protected from the rain, complete 

 their development. As they ripen, the stalk elongates, 

 becomes erect and rigid, and raises the fruits into a favour- 

 able position for dispersal. 



The power of movement in plants is an important aid 

 to protection. By this means, during suitable sunlight, 

 leaves are placed in the most favourable position for 

 photosynthesis ; during intense light, the adoption of the 

 edgewise position protects the chlorophyll against decom- 

 position ; leaves and leaflets applied to one another reduce 

 the exposed surface and check loss of water by transpiration 

 and loss of heat by radiation. Flower-movements protect 

 the honey and pollen from rain and from useless insects, 

 and finally the fruits when ripe are moved into the most 

 favourable position for seed-dispersal. 



