126 BIOLOGY FOR BEGINNERS 



4. Dispersal. 



Reason for dispersal. 

 Means of dispersal: 



1. Wind, adaptations for wind dispersal. 



Tufts of down (dandelion, thistle). 

 Wings (maple, ash, elm). 



2. Animals, adaptations for animal dispersal. 



Burs (burdock). 



Hooks ("pitchforks"). 



Edible flesh (peach). 



Hard or bitter "pits" (why?) 



Bad tasting when unripe (why?) 



3. Water. 



4. Mechanical devices. 



Explosive fruits (touch-me-not). 

 Pinching fruits (witch hazel). 

 Whipping fruits (poppy, mullein). 



5. Economic Importance. 



Plant propagation. 



Food supply (cereals and fleshy fruits). 



Cotton fiber. 



Harmful weed seeds. 



Poisonous fruits. 



