DICOTYLEDONS: MYRTALES. 



689 



and the lip below. Move a pencil into a flower, endeavoring to imitate the 

 entrance of an insect, and try to determine how cross-pollination takes 

 place. Compare the blue flowers of the blue violet. 



The small closed flowers are called cleistogamous, and they are self- 

 pollinated, because being closed, and because of the position of the anthers 

 around the stigma, the pollen from the opening anthers comes directly in 

 contact with the stigma. In the flowers of the pansy cross-pollination 

 often takes place through the agency 

 of insects. While the blue flowers 

 of the blue violet rarely set fruit, 

 nevertheless pollination and fertili- 

 zation do take place in some of the 

 flowers, though fruit sets more abun- 

 dantly in the cleistogamous flowers. 



Material. Entire plants with the 

 flowers; collect some early in the sea- 

 son when the blue flowers are abun- 

 dant, and some later when the small 

 flowers underneath the soil or leaves 

 are formed. Mature fruit is also 

 desirable. 



Topic IX: Dicotyledons 

 with distinct petals and 

 epigynous flowers. 



ORDER MYRTALES. 



1180. Lesson XVII. The even- 

 ing-primrose family (Onagra- 



cese). In the evening primrose 

 (oenothera) the flowers are ar- 

 ranged in a loose spike along 

 the end of the stem, each one 

 situated in the axil of a leaf- 

 like bract. The flowers of the 

 family are very characteristic, as shown here. They are sessile 

 in the axil of the bract, and the calyx forms a long tube by the 

 union of the sepals, only the end of the tube being divided into 

 the individual parts, showing four lobes. On the edge of the 

 open end of the calyx-tube are seated the four, somewhat heart- 



Fig. 576. 



Section of flower 

 of CEnothera. 



