SURROUNDINGS OF THE HOME 267 



currant, and grape to start new plants, by bedding the lower 

 ends of these " cuttings" in moist earth till they develop 

 roots. 



SUMMARY 



The root, stem, and leaf are the parts of a plant directly concerned 

 in its nourishment and perfection. Its buds, flowers, and fruit are for 

 the purpose of continuing the species. 



The roots hold the plant firmly in place in the soil. Through them 

 comes the water, and the minerals held in solution by the water, out of 

 which in part the plant manufactures material for its own growth, 

 and food for man and other animals. 



Through the leaves the plant rids itself of surplus water from the 

 sap by the process known as transpiration. From the air through their 

 leaves plants get carbon dioxide gas which is the other important raw 

 material for the manufacture of food in plant growth. 



Only plants can manufacture starch, sugar, oils, and proteins out 

 of water, carbon dioxide, nitrogen compounds, and some few other 

 substances taken from the soil. This chemical change occurs chiefly 

 in the leaves when exposed to sunlight. 



Seeds and their protecting envelope constitute the fruit of the plant. 

 While many times these fruits are edible, sometimes seeds and all, in 

 other cases the husks, rind, or shell serves no purpose other than as a 

 protection to the seeds. Tomatoes, pumpkins, and squashes are fruits 

 by this definition as much as are cherries, apples, and oranges. 



At the inner end of the style of a pistil is the ovule which before it 

 can develop into a seed must be fertilized. This is accomplished by the 

 growth of a pollen grain from the stigma down through the style and 

 into the ovule. In many plants the pollen is developed in the anthers 

 of stamens in the same flowers that bear the pistils, and self-fertiliza- 

 tion may take place. In other cases the pollen comes from other 

 flowers on other plants and cross-fertilization occurs. 



Many plants are propagated naturally by bulbs, by underground 

 stems, by stems above ground known as runners, or by sprouts arising 

 from buds developed around the base of the stem below ground. 

 Plants are propagated artificially by grafting, budding, and by use of 

 cuttings. 



In studies of the same kind of plants it soon becomes apparent that 

 there are wide differences other than of size. It is also apparent that 

 plants adapt themselves to varying conditions. Even the leaves on 

 the same plant often show marked variations in form. 



