DESCRIPTION OF THE COBN PLANT 29 



to light. Late in the season, when the soil is well shaded, 

 roots will be found very near the surface ; but ordinarily, 

 during the growing season, they are 3 to 4 inches below. 

 The method of planting may also exercise some influence 

 on the depth of upper roots. At the Kansas station,' 

 where the root systems of " listed " corn were compared 

 with those of surface-planted, the upper roots of the 

 former were found to average about 1 inch deeper during 

 the cultivating season, especially near the plant, thus 

 permitting deeper cultivation. 



14. Types of roots. — Maize roots may be classed as 

 primary roots, brace roots, lateral roots, and hair roots. 

 The main roots are those having their origin at the base 

 of the stem ; they are twenty to thirty in number and 

 4 to 6 feet in length. The lateral roots are numerous small 

 roots thrown off from these, and they again may produce 

 other laterals. Their number is very large and may aver- 

 age several hundred to each main root; in length they 

 vary from less than 1 inch to 1 or 2 feet. The root-hairs 

 are microscopic in size, single-celled, and infinite in number. 

 They are borne on the main roots in their earlier growth, 

 and on all the laterals. Root-hairs are short-lived and 

 limited to the newer root growth, or rather to a zone near 

 the growing point of the roots. They are absorbent or- 

 gans, and do not grow to be roots. 



15. The proportion of root. — The total weight of the 

 root in a corn plant has been found to be about 12 to 15 

 per cent of the weight of the total plant, including the 

 ear .2 The total length of roots laid end to end, of a single 

 plant of small grain, as wheat or oats, has been estimated 

 at ,1600 feet ; but in a corn plant it would be greater. 



1 Kan. AgT. Exp. Sta., Bui. iS7;203. 



2 KiES&ELBACH. Nebr. Agr. Exp. Sta., Rpt. 1910 : 131. 



