Pollinatioji and Fertilization 



165 



Flowers are not at home to all visitors. The sticky juice 

 covering the upper portion of the stems of Heaths and of other 

 flowers prevents ants from scaling the heights to rob the honey 

 within the flower. Flowers are often closed when unwelcome 

 guests are flying about. The opening and closing of flowers 

 at certain times of the day led Linn^us to arrange a floral 

 clock, but the movements of flowers, like those of leaves, are 

 regulated by varying conditions of temperature and sunshine, 

 so it would not do to depend upon 

 such a timepiece for getting to 

 school in time. 



When moths and beetles are 

 flying about our lamps, have you 

 ever wondered what they are about 

 so late at night? It will be worth 

 while to visit flowers with a lantern 

 to find out. 



The story of the Yucca and its 

 moth has been often told since it 

 was found by Mr. Riley and Dr. 

 Engelmann,! but it is so interesting 

 that it will bear repeating. The 

 Yucca, which bears its majestic 

 panicles in many of our gardens 

 from November till January, has 

 come from Mexico. The flowers 

 are scentless during the day, but give 

 forth their fragrance, as do so many 

 of our flowers, only to attract night 

 visitors. Have you ever seen the 

 seeds after flowering ? For sixteen 

 years the flowers of one plant have 

 been watched, and sixteen times 

 they have withered and are cut off, 

 for Nature retains no useless burdens 



Fig. 163. — The Pronuba moth 

 gathering pollen from the 

 stamen of Yucca to carry 

 10 the stigma. (From the 

 *' Popular Science Alonth- 



ly"-) 

 The moth which can 



aid in quickening the seeds has been left behind in Mexico. 



illustrated books of Dr. Bolus on South African Orchids will help you to 

 understand the flowers. 



1 C. V. Riley, Missouri Experiment Station Report, 1892. 



