86 FiaST STUDIES IN PLANT LIFE 



XIY.— HOW LEAVES PROTECT THEMSELVES. 



1. N'ery wonderful are the plans by which leaves are 

 protected from cold, from heat and from animals. 



2. How leaves are protected from cold. Have 

 you ever noticed the blackened leaves on a pitipsporum 

 hedge after a frosty night in spring ? All tender 

 leaves are easily hm-t on a clear, cold night, when 

 there are no clouds to act as blankets to the earth and 

 to the life upon it. During the day a leaf is spread 

 out with its face to tlie sky. If tender leaves like 

 those of the clover were kept in this position at night, 

 they would soon lose all their heat and be in danger 

 of frost-bite. Some leaves, thfrefore, tuck themselves 

 up snugly for the night. 



3. "Watch a clover plant, and you will see how it is 

 done. By day, the clover spreads out its three pretty 

 leaflets to the sun (fig. 62). At nightfall the two 

 opposite leaflets fall down, and come close together ; and 



then the third leaflet bends gradually o^'er 

 until it forms a roof to cover the other 

 two ! It is the upper side of the leaf 

 that most needs protection from cold, 

 and, by this plan, all the upper sides are 

 covered.* You can now look for yom-- 

 selves at the many plans for keeping the 

 cioverieafletB ^old froiTi leaves when they are just 

 "''uigK"'^ leaving the bud. Fig. 63 will show you 



*0n Mt. Kosciusko, and other high points, plants are often hairier than the 

 same plants on thoplains, in order to pvotoct Iheni from the mountain cold. 



