THE WORK OF FRUITS 



323 



ments of seeds, especially the parachutes, impaired by 



rain and dew? Test them by placing them in water; 



are they readily wetted ? You have probably noticed 



that fruiting Dandelion heads open 



only in dry, sunny weather, when 



the seeds can fly to best advantage; 



at the approach of rain they close 



up tight, so that the tiny parachutes 



are kept perfectly dry. Study also 



the Willow Herb (Epilobium) and the 



Pines in this connection. In many 173 . Hop fruiti which flies 



cases you will find that while the by means of a bract - 



seeds are not protected from 

 rain, and may become drenched, 

 yet they do not become de- 

 tached from the parent plant 

 until perfectly dried out and in 

 condition for flying. 



The burs, " stickers," and 

 ^ other troublesome fruits which 



wall of the seed-case (ovary). attach themselves to Clothing, 



show how easily plants distribute them- 

 selves by means of animals. Usu- 

 ally the organs of attachment are not 

 borne on the seed itself, but on the 

 ovary -wall, on bracts or on the stem 

 or flower -stalk. On examining such 

 fruits (Figs. 175 to 178) with a hand- 175. Burdock head. 



