200 



FIRST TEAR SCIENCE 



transporting of the food, the work of the plant cannot be 

 carried on, and the plant dies. It is on account of this 

 that many plants are especially prepared to retain their 

 water supply. In almost all plants the stomata, or little 

 pores in the leaf through which the water passes out, close 

 up when too much water is being lost. 



In some plants, like the corn, when the root cannot 

 supply sufficient moisture, the leaves curl up and thus 

 ___ present less surface for evapora- 

 tion. In trees like the eucalyp- 

 tus the leaves hang vertically 

 when the sun gets too bright 

 and present their edges to the 

 sun's rays. Some leaves, like 

 the sage, are especially prepared 

 to conserve their moisture by 

 having their surfaces covered 

 with hairs. Others have a 

 waxy covering, as the cabbage 

 and the rubber tree. In some 

 plants the leaves are very 'small 

 and have few pores, as the 

 greasewood of the desert, and some have done away with 

 leaves altogether, as the cactus. It is because the roots 

 cannot supply sufficient moisture where the ground freezes 

 in the winter that trees having large leaves shed them, and 

 only trees like the pine whose needle-like, waxy leaves give 

 off almost no moisture can retain theirs. 



95, Flowers. The 1 stem not only bears leaves but, in 

 the higher kinds of plants, it bears flowers. The function 

 of the flower is to produce seeds and provide for the con- 

 tinued existence of its kind. If the flower of a buttercup, 

 quince, cassia, or geranium is examined, it will be found to 

 be made up of four distinct kinds of structures. 



EUCALYPTUS LEAVES. 



