200 STEMS 



cambium to the duration of life of plants in temperate regions. 

 21. How is the secondary growth of plants with scattered bundles 

 accomplished? Give examples. 22. What are some of the common 

 kinds of plants which have scattered bundles ? 



F. 23. Describe tracheary vessels and fibers as to structure and 

 function. 24. Explain why dead tracheary vessels are of more 

 service to the plant than live ones. 25. Describe sieve vessels as to 

 structure and function, defining companion cells. 26. Define mestome 

 and stereome. 



G. 27. Describe heartwood and sapwood. 28. Explain the forma- 

 tion of the rings in wood. To what extent are these rings annual ? 



H. 2Q. Describe the structure and functions of the bark of trees, 

 defining girdling. 30. Describe lenticels and the advantages to the 

 plants in having them. 



I. 31. Describe grafting and budding, defining stock and scion. 



SECTION 51. i. Name the two great divisions of spermatophytes 

 and describe a fundamental character in which they are different. 



2. What is the ovary of plants ? 3. Name the two great divisions of 

 angiosperms and explain the meaning of these names. 4. What is 

 meant by "natural " groups of plants, and how are they determined ? 

 5. What two of the three great divisions of spermatophytes have the 

 cylindrical arrangement of bundles ? 6. Give examples of mono- 

 cotyledons. 7. Explain the terms endogen and exogen and tell why 

 these terms were abandoned. 



SECTION 52. i. Describe the structure of buds and their use to 

 plants. 2. When did the buds which open in spring first appear? 



3. Explain why a freeze while the fruit blossoms are open may not 

 entirely prevent a crop. How can you tell whether the young fruit 

 has been destroyed by a frost ? 4. What is the difference between a 

 frost and a freeze ? 5. Describe two ways of classifying buds, defining 

 the terms used. 6. Explain a method of distinguishing leaflets from 

 simple leaves. 7. Describe the method of branching of the lilac. 

 8. Discuss the advantage of overproduction of buds, giving ex- 

 amples. 



SECTION 53. i. Explain the objection to the use of the word storage 

 as applied to plants. 2. Give examples of the accumulation of sub- 

 stances in plants and state advantages which ensue therefrom. 

 3. Describe latex and give examples of it, defining caoutchouc. 



