84 BOTANY: PRINCIPLES AND PROBLEMS 



288. Some plants wilt much more readily than others. What factors 

 may be responsible for these differences? 



289. Why is a wilted plant unable to carry on its functions as well as 

 one that is in a normal, turgid condition? 



290. Why will a plant sometimes wilt even though the soil in which it 

 is growing is abundantly supplied with water? 



291. Why does a plant which has wilted in the daytime usually revive 

 at night, even though no rain falls? 



292. If a tree is subjected to a severe drought, its leaves wilt but its 

 twigs remain rigid. Explain. 



293. In using foliage for wreaths or other decorations, would you 

 choose young leaves or mature leaves? Why? 



294. The stomata often tend to close in the middle of a hot day. 

 Explain why this is so and how it is of advantage to the plant. 



295. Do stomata tend to open or close if the leaf is exposed to the 

 light? Explain. 



296. How will stomata tend to act during the course of a normal 

 period of twentj'^-four hours during the summer? 



297. What is the best time of day to pick flowers, if it is desired to 

 keep them fresh for a long time out of water? 



298. Why will cut flowers remain fresh longer if they have been placed 

 in water for a few hours directly after being picked? 



299. Do you think that the water requirement of a plant will be higher 

 if it is grown on rich soil or if it is grown on poor soil? Why? 



300. Do you think that the water requirement of a plant will be higher 

 if it is grown on moist soil or if it is grown on dry soil? Why? 



301. Do you think that the amount of cultivation which a plant 

 receives will have any effect on its water requirement? Explain. 



302. Assuming that the water requirement of corn under a given set 

 of conditions is 400, and that a bucket holds 10 liters, how many buckets 

 of water have passed by transpiration through a corn plant the dry 

 weight of which is 200 grams? 



303. Given the same conditions as in Question 302, assume further 

 that three such corn plants are planted in each hill and that the hills are 

 one meter apart each way. If all the water which passes through these 

 plants by transpiration during the season could be collected, how deep 

 a layer would it make over the surface of the field? 



