I'ACIFIC TREE AND VINE 



How Plants 



Protect Themselves 



A single leaf of an apple tree has 

 one hundred thousand pores, and 

 through every one of these water is 

 constantly pssing off into the sur- 

 rounding atmosphere. Air has an 

 enormous appetite for water, and 

 the drier it is the mote it takes up. 



Considering the way in which 

 the atmosphere is constantly forc- 

 ing the apple tree and every other 

 plant to give up its moisture, the 



plants is more valuable than gold 

 is to human beings, and where the 

 supply is scanty they have learned 

 to hoard it as carefully as a laiser 

 does his treasure. Plants cannot 

 refuse to give up water altogether, 

 for otherwise they could not grow. 

 All their food is taken up by their 

 roots, dissolved in water. This 

 sap rises through their veins and 

 feeds them. Thev make use of the 



side is exposed to the direct rays of 

 the sun. The glaze prevents the 

 hot rays sucking all the water out 

 of the leaf. Some plants, indeed, 

 refuse eniirely to part with water 

 through the ujiper side of the leaf. 

 Laurustinus and lilac leaves have 

 no pores at all on the shiny upper 

 surface of the leaves. 



Pine trees inhabit dry, sandv 

 soils. These refuse to grow wide 

 leaves, but confine themselves to 

 producing thick, fleshy needles, 

 which have very few openings 

 through which water can escape. 



marvel is that after a very few days 

 of hot sunshine every plant does 

 not wither and dry up. Yei even 

 those growing in light soil and ex 

 posed situations manage to with- 

 stand weeks of drought without 

 los'ng their greenness. More mar- 

 velous still, acacias and cacti will 

 grow and remain green out on the 

 fiery desert in Africa and Arizona. 

 Plants, like all oilier living things, 

 have learned to adaj)! themselves to 

 their situations, and to lake ])re- 

 cautious accordingly. Water to 



mineral matter, and then let the 

 wa'er which contained it escape 

 through their lungs — that is, their 

 leaves. 



But their methods of holding on 

 to sufiicient water to keep them 

 a:reen and flourishing are manvand 

 ingenious. Go out and pick a leaf 

 from any plant or shrub — a hav\'- 

 thorn leaf, for instance. Von will 

 notice that its u[)i)er side is much 

 smoother than the under. 



The upper side looks dull in com- 

 parison. This is because the upper 



Cabbages need an enormous quan- 

 titv of water, but unless the supply 

 was absoluetly unlimited their big 

 leaves would give up so much to 

 the air that, without some means of 

 checking this over liberality, the> 

 would wilt and die. 



Cut a fresh cabbage leaf and ex- 

 amine it. It has a sort of dusty, 

 mealy look. Put the leaf under a 

 microscope an you will see thai 

 this bloom is composed of tiny 

 needles of wax. The cabbage has 

 produced the wax to protect itself 



