112 



DICOTYLEDONS 



of the leaf. This can be best obtained by keeping the leaves in 

 water for a month or two. 



3. The Teak Tree a tropophilous'' Plant- — From the observations 

 we have made above we learn that the Teak is adapted to the 

 various conditions of the climate. The Mangrove (page 51), and 

 the Cactus (page 57) are xerophilous in their structure, i.e., they 

 possess various contrivances to check the transpiration of Avater. 

 Other plants, like the Garden Balsam (page 21), have a hygro- 

 philous structure, characterised by large leaves with a thin epi- 

 dermis to allow the water to evaporate freely. 



The Teak combines the two types. It is hygrophilous at one 

 time, viz., the monsoon producing large and numerous leaves to 

 transpire large quantities of water, and growing luxuriantly; 

 and xerophilous at another time, viz., the dry season, diminishing 

 the process of transpiration by shedding its leaves and stopping 

 its growth. Other trees that shed 

 their leaves in the dry season are 

 the Silk Cotton tree [Bomhax, 

 p. 1 5) the Pagoda tree {Pliimieria, 

 p. 82) and the Coral tree (Enj- 

 tJirlna, p. 39). 



We call such plants 

 tropophilous. The same 

 is observed in most trees 

 growing in cooler climates. 

 There, it is during winter 

 that plants cannot obtain 

 water, because, though 

 there is plenty of it in 

 the ground, it is frozen. 

 And as they can obtain 

 nothing or almost nothing, 

 they cannot spend niiicli. 

 Therefore they shed their 

 leaves in the beginning of winter, and become x('r()[)hilous. Water 



Toak tree (Teclona f/viindis). 

 Much reduced. 



*From the Greek trepo, to turn. 



