378 THE HIGHER DICOTYLEDONS. 



newly-opened flower (in which the style has not yet grown 

 out), and note the thread of pollen which emerges. 



Next carefully slit open the corollas of a few young flowers 

 removed from the flower-head, set the flowers in a watch- 

 glass or on a glass slide under a bell- jar for a few minutes (to 

 let them recover), then touch the filaments and note their 

 writhing contraction. Each filament can be made to contract 

 independently, pulling the anther-tube over to the corre- 

 sponding side, as well as drawing it downwards, so that the 

 pollen-mass present above the style is squeezed out and 

 carried away on the insect's head. 



Artemisia (Mugwort, Wormwood) is peculiar in having 

 flowers adapted to wind-pollination. The pollen-grains are 

 smooth (not spiny or ridged, as in other Composites), dry, 

 and powdery, and the small dingy flower-heads are on long 

 flowering stems carried well above the large leaves ; the heads 

 droop in Sea Wormwood. The anther- tube projects a little 

 beyond the tubular corolla, and has bristles on its upper 

 edge which hold the pollen in a sort of basket, so that it may 

 be gradually blown away. Then the style emerges and the 

 stigmas spread out ; each stigma has a large f anlike fringed 

 end, presenting a large surface to receive pollen. 



QUESTIONS ON CHAPTER XIV. 



1. Draw up a comparison between Primrose and Cowslip as to 

 habitat, leaf, inflorescence, and flower. 



2. Describe the structure of a Primrose flower, pointing out the 

 differences between the two types of flower. 



3. Describe and discuss the pollination of the Primrose. Do you 

 consider heterostyly plays an important part in promoting cross- 

 pollination ? Give reasons for your answer. 



4. Describe the pollination of the Cowslip, and point out how it 

 differs from the Primrose. 



5. Describe the fruit of Primrose and Cowslip. 



6. Draw the floral diagram of a Primrose, and sketch in longitudinal 

 section the two forms of the flower. How do you account for the 

 unusual position of the stamens in relation to the lobes of the corolla ? 

 How do you infer the number of the carpels ? 



