26 



HOW PLANTS GROW 



FIG. 13. Young radish 

 plants. 



water to rise through the stem and to supply all the cells 

 with water and with food. 



The Stem. The stem bears the 

 leaves, buds, flowers, and fruit or 

 seeds. In upright-growing plants, 

 the stem supports these parts at 

 some distance above the earth; 

 sometimes, as in the grape-vine, the 

 stem climbs upon other objects for 

 support; sometimes, as in the mel- 

 on, it creeps on the ground; in 

 other plants, as the potato and quack 

 grass, it may even grow in part un- 

 derground. (Figure 14.) As we 

 have learned in Lesson 3, the stem 

 is the channel through which the 

 food prepared in the leaves passes to the roots. 



The Leaves. The leaves grow out from the stem at 

 regular places. If we hold a leaf toward the light, and 

 place a finger behind it, we find that the light can pass 

 through the leaf. As we learned in Lesson 4, the sun- 

 light shining through the leaf cells prepares the food 

 for the cells of the whole plant. The cells of the leaf 

 are arranged in thin plates to expose a very large number 

 of them to the action of the sunlight. (See Figure n.) 

 The cell walls are transparent as glass. The leaves look 

 green because their cells contain green chlorophyll. 



Leaves Necessary. We learned in Lesson 4 that the 

 health of the plant depends much upon the health of its 

 leaves. If the leaves are eaten by insects, or if they are 

 picked off or broken, they can not prepare food, and 



