10 PLANT LIFE 



wilting will take place in a short time. Compare it with a similar 

 plant placed in fresh water at the same time. 



Water must be supplied to the soil to make the density of the 

 soil water less than that of the sap in the roots. When conditions 

 are thus favorable growth may follow. During the normal process 

 the plants give off a very little liquid to the soil in exchange for a 

 large quantity of very dilute liquid made up of a large quantity 

 of water and a very slight trace of plant food in solution. The 

 liquid given off by plants at the roots usually has an acid reaction 

 and is sometimes useful in dissolving lime, phosphates and other 

 minerals in the soil. It thus becomes changed in its character and 

 when diluted may be later taken up by the roots. 



In certain other cases where the soil conditions are unfavor- 

 able the liquid thrown out by roots may remain in the soil, and until 

 it is changed has a poisonous effect upon the plant. The action 

 of air and water during the process of tillage will help to remove 

 or change this poisonous substance. This makes the soil again 

 suitable for plant growth. 



THE PLANT AND THE SEASONS 



In the temperate climates of the globe the change of season 

 during the year is so regular that plant growth has adjusted itself 

 to the extremes of winter and summer. In the more northern 

 parts of the temperate zone the changes are more pronounced 

 than in the extreme south. 



Examples of the preparation for winter are found among all 

 plants in the ripening of fruits and seeds in the fall. Woody 

 plants and other perennials form buds and some means of protec- 

 tion, as the formation of scales, waxy or downy growth, lenticel 

 or corky growth on the leaf scars near the buds. 



In early fall while leaves are still upon the trees examine twigs 

 of various fruit trees, such as apple, peach, and plum. Study the 

 protective coats found on the buds. See if any of the leaves will 

 snap off readily, indicating the formation of a natural separation 

 from the twig which will leave a leaf scar. If this study is made in 

 the winter the protection of the buds may be shown even better 

 and leaf scars may show corky growth. The surfaces of young 

 twigs will show more protection. The green color is then destroyed 

 and breathing pores are filled with corky growth. 



The orchardist understands the need of checking the growth 

 of his fruit trees in early fall by the growth of a cover crop to use 



