CHAPTER IV 

 GRAIN CROPS 



PLANT STRUCTURE 



Parts of Plant. — All the more important plants, in which 

 the farmer is chiefly interested, have four distinct parts, 

 roots, stems, leaves, and flowers. Plants, like animals, 

 vary greatly. This fact is true of plants in any one variety, 

 such as wheat plants or pansy plants. This habit of varia- 

 tion has made possible the development of the great variety 

 of plants that are grown to. supply the many different needs 

 of man. In some plants one part has been developed for 

 use, in other plants other parts. For example, in the 

 turnips the root is eaten; in asparagus the stems; in lettuce 

 the leaves; and in wheat the seeds. 



Roots. — There are two kinds of roots, fibrous roots and 

 tap roots Roots grow in the soil and take up moisture 

 and plant food. The moisture in the soil and the plant 

 food with it pass through the thin walls of the roots and 

 very fine root hairs, or branch roots. Roots also hold the 

 plant in place and tend to keep it erect. 



Stems. — These may grow erect like corn or wheat or may 

 trail along the ground like squash or cucumber vines, or 

 they may climb up some other object, like peas or beans. 

 The function or work of the stem is to bear the leaves and 

 blossoms and to provide a means for the plant food to go, 

 to and from the leaves. Plant food and moisture circulate 

 in the plant somewhat similar to the circulation of blood 

 in the body of an animal. In some cases, like potatoes, 

 for example, some of the stems grow under ground; in fact, 

 the potato (tuber) that we eat is simply an enlarged stem. 

 This fact is indicated by the eyes on the potato, which are 

 the buds from which branches may grow. 



Leaves have been called the stomach of the plant, 

 because it is in the leaves that the plant food from the soil 

 and from the air are brought together and changed into 

 the compounds which make up the plant. From 300 to 



