THE STEMS AXD FOLIAGE OF PLANTS 



Characteristic of Dry Kegions. 



As we are going to study plants of a region charac- 

 terized by great drought, we will now pay a little 

 attention to the general features of the vegetative organs 

 of the natives of such a country, as their special 

 adaptations to a dry soil and air, and a paucity of 

 water during the summer, are very pronounced both in 

 the stems and leaves of many plants. 



After the rainy season, plants which maintain a 

 show of foliage only during the period of seasonal rains, 

 and dry off with the advance of drought, exhibit quite a 

 different sort of leaves from those borne by plants which 

 persist all the year round, and therefore have to 

 withstand a long period of drought. Take the many 

 species of Ox'alis. They have thin and bright green 

 leaves ; but think of the shrubs in January. They 

 bear leaves almost leathery in character, such, for 

 example, as the Sugar-bush and Wagen-boom. Their 

 toughness is due to the thick skins they have, which 

 prevent water escaping too quickly in the dry summer. 



