HOW LEAVES PROTECT THEMSELVES 



87 



How the 

 three 1 e a f- 

 lets of t h e 

 clover or the 

 wood-sorrel 

 are folded 

 before open- 

 ing. 



one plan, but there are many others. Look at the 

 top of a gum sapHng and try to find how the tender 

 young leaves are guarded from cold. Gum 

 leaves hang downwards : why do the baby- 

 leaves point upwards? The plans for 

 guarding leaves against heat are chiefly of 

 two kinds : plans for storing up water, and 

 plans for checking the loss of it. 



5. Leaves that store water. Look at 

 the weed called portulaca or purslane which 

 overruns our gardens in the summer, and 

 you will see that the leaf is thick and fleshy, 

 and full of water. Here 

 is a plant that revels 

 in the hottest sun- 

 shine. Then there 

 are the stone-crops 

 and the morning 

 flowers that make so 

 many dry places gay 

 with their star-like 

 flowers. In these, and 

 in many other plants, 

 the fleshy stem works 

 like the leaf in the 

 task of getting food 

 from the air. Then 

 there are the thick- 

 leaved cactuses that 

 we have brought 

 from hot desert lands 

 into our gardens. 



Fig- bif 



Morning flower, showing fleshy leaves. 



