154 FIELD CROPS FOR THE COTTON-BELT 



States where the growing season is relatively short corn 

 plants are not nearly so tall as in the southern United 

 States. The diameter of an average corn stem between 

 the first and second nodes in most field varieties will be 

 from one to one and a half inches. 



195. Structure of the stem. — The culm of corn is 

 made up of a succession of nodes and internodes. It differs 

 from that of other cereals in that it is filled with pith rather 

 than being hollow. The internodes of the corn stem are 

 short at the base, gradually increasing in length toward 

 the upper end, — a modification which adds strength to the 

 culm. That portion of the culm which extends beneath the 

 ground surface is composed of a series of six or eight short 

 nodes, each bearing a whorl of roots. The above-ground 

 nodes serve as points of attachment for the leaves, the 

 ear-branches, and the tillers. Each above-ground node 

 bears a leaf and also a bud. With most varieties binder 

 normal conditions, only one or two of the buds develop, 

 the others remaining dormant. 



A number of the above-ground internodes of com are 

 alternately grooved or flattened. Each groove is covered 

 by a leaf-sheath and accommodates the embryonic ear or- 

 the young ear-branch as the case may be. 



If a cross-section of the com stem ip examined, it will be 

 seen that the outer covering of the stem is a thin shell of 

 hard tissue which is really a mass of closely woven fibro- 

 vascular bundles. The chief function of this outer tissue 

 is to give strength and rigidity to the stem. The central 

 portion of the stem is composed of a mass of large and 

 loosely arranged parenchyma cells known as the pith. 

 Throughout this loose mass of tissue are the fibrous strands 

 or fibro-vascular bundles which serve as the circulatory 

 ducts for the water and dissolved food in theii; passage 



