QUESTIONS AND SUGGESTIONS 255 



this remarkable habit and the advantage which it may be 

 to the plant have not yet been satisfactorily explained. 



Fig. 93. — Leaves of sun-dew magnified, showing the method of capturing an insect. 



QUESTIONS AND SUGGESTIONS 



Section 54. 1. Define leaves as to structure, function, and origin. 



A. 2. Discuss the value of leaves to man. 



B. 3. Describe a leaf externally and internally, naming its prin- 

 cipal organs and tissues and indicating their functions. 



Section 55- A. 1. Describe the venation of leaves, comparing 

 monocotyledons with dicotyledons. 2. Define pinnate and palmate 

 leaves, giving examples. 



B. 3. Illustrate by examples of leaves the principle that organs 

 vary in their power to vary. 4. Define and give examples of linear 

 and ovate leaves. 5. Define and give examples of entire, toothed, 

 and lobed leaves. 6. Distinguish between pinnately and palmately 

 compound leaves, giving examples. 



C. 7. Define pulvinus, stipule, sessile, clasping, and sheathing. 

 8. Describe the opposite, alternate, and whorled arrangements of 

 leaves and give examples. 9. Describe gradation in the length of 

 petioles, explaining the advantage thereof, and defining rosette. 



D. 10. Describe glaucous and pubescent leaves, giving examples, 

 n. Discuss the advantage of hairiness to leaves. 12. What are three 

 characteristics of leaves of the heath family, and in what regions are 

 members of this family most abundant ? 



