22 BOTANY: PRINCIPLES AND PROBLEMS 



47. Name ten cultivated plants in which the stem is the organ useful 

 to man. 



48. The blade of an ordinary leaf is broad and thin. Explain the 

 advantage of this to the plant. 



49. Name ten cultivated plants in which the leaf is the organ useful 

 to man. 



50. What makes reproduction necessary among plants and animals? 



51. Name ten cultivated plants in which the fruit or seed is the organ 

 useful to man. 



52. What important resemblances are there between the physiology 

 of a typical plant and of a typical animal? What important physio- 

 logical differences are there between these two groups of organisms? 



REFERENCE PROBLEMS 



9. Are there more species of plants or of animals on the earth today? 



10. Are there any plants which lack roots? which lack leaves? which lack 

 a stem? which lack reproductive organs? 



11. Give the derivation of each of the following terms and explain in wliat 

 way it is an appropriate one: 



Thallophyte Bryophyte Pteridophyte 



Spermatophyte 



