60 SOUTH AFRICAN BOTANY 
2. Describe each of the following :— 
(a) A bulb; 
(b) A tuber ; 
(c) A rhizome ; 
(d) A tuberous root. 
State what purpose they serve in the life history of the plant. 
Give an example and a sketch of each. 
3. What are the characters of stems as distinguished from 
roots? What is meant by a bud? Explain the difference 
between terminal, axillary and adventitious buds. 
4, Give an account of the characteristic features, the oceur- 
rence and functions of cork tissue. 
5. Describe the structure of the stem of an aloe, and give 
an account of the process by which it increases up to a certain 
age and then no more. 
6. Compare the structure of the stem of a dicotyledonous 
plant with that of a monocotyledon. 
7. Describe with examples the various forms assumed by an 
underground stem, 
8. What are lenticels? Mention two plants in which you 
have seen them. Wheredo they occur? Make sketches to show 
as exactly as possible their external appearance, 
Explain precisely— 
(a) How lenticels are formed, and 
(b) What is their function. 
9. Make diagrammatic drawings of transverse sections of the 
stem and root of the sunflower (or of any other dicotyledonous 
root you have studied) to show how the arrangement of the 
various tissues differs in stem and root. Label all the parts, and 
indicate the position of the protoxylem, Explain how the dif- 
ference in the arrangement of their tissues is related to the 
difference in the work done by the two. 
10, Make a large sketch of the cross-section of a one-year- 
old stem of an oak to show the arrangement of the tissues. 
Name the tissues shown (the detailed microscopic structure is 
not expected), Make a similar sketch of the same stem when 
four years old. Write a brief account of secondary thickening 
in the stem of this plant. : 
