THE LEAF 147 
sunlight, and protects against wind and running 
water. The apex may be acute, obtuse, or pungent. 
Leaves may be sessile or petiolate. Grasses show a 
ligule. Stipules are outgrowths of the petiole base. 
The leaves of pitcher plants and sundews trap insects. 
Complete parasites have no leaves. Compare foliage and 
seed-leaves. 
“po 
~ 
10. 
Li, 
15. 
16. 
QUESTIONS ON CHAPTER V. 
- What do you consider the twelve most important facts 
about leaves? 
- What leaves are used by man? For what purposes are 
they used? ~ 
- Define the terms venation, pinnate, palmate, serrate, 
linear, obovate, giving examples of each. 
. What are the chief functions of leaves? 
- What is transpiration? How is it regulated? What 
experiments have you made relating to transpiration? 
- How can you show the course taken by the transpiration 
current ? 
. Under what circumstances must plants check transpira- 
tion? Explain a few of the ways in which this is done. 
- What is respiration? How does it differ in plants and 
animals? 
- How would you show (a) that the green parts of a plant 
give off oxygen, (0) that carbon dioxide is given off 
by a plant? 
The leaf is the factory of the plant. Explain this. 
What is photosynthesis? How did you show that sunlight 
and chlorophyll are necessary to photosynthesis? 
. Describe the tissues of a leaf. State all you can find out 
without a microscope, and explain the function of each 
part. 
. Where does a plant get its carbon from? 
. How are leaves protected against cold, heat, wind, and 
grazing animals? 
What circumstances determine the shapes of leaves? 
Give a summary of the gaseous exchanges of a plant. 
