STRUCTURE OF MAIZE 141 



while just above the permanent roots it was three-eighths by five- 

 eighths inch. The majority of the permanent roots begin at 

 about one inch below the surface of the soil, regardless of the 

 depth of planting. Brace roots, however, usually start from the 

 node, one or two inches above ground. The aerial portion is 

 much enlarged, but soon after entering the ground becomes 

 reduced to the size of the other roots. A maize plant fort}'-three 

 days old and five feet high was found to possess thirty-five roots, 

 eleven of which were brace roots. None of the brace roots had 

 entered the ground more than one and one-half inches. Their 

 total length varied from one and one-half to five inches. An 

 examination of the mature plants shows the brace roots to have 

 grown to considerable depths, thus performing the function of 

 true roots. Variety differences in ability to support the culm 

 and prevent its being blo^Mi do^\Ti have been obser\-ed, but this 

 character has not as yet been made of practical value.^ 



210. Culms. — The maize plant is the most variable in size 

 of the cereals. The height is reported to vary from eighteen 

 inches in the Tom Thumb pop to thirty feet or more in the 

 West Indies. Individual stalks tvvent}^-two and one-fourth feet 

 high have been reported from Tennessee. From four to twelve 

 feet is a common variation. The height varies not only with the 

 variety but the same variety varies largely with soil and climatic 

 conditions. Along the Mississippi River, south of the fortieth 

 parallel, it is not unusual to see maize growing on which the ears 

 are so high that a man of ordinary height can barely reach them. 

 In the northern latitudes of the United States, as in New Eng- 

 land, much maize is so short as to make it necessary to stoop to 

 reach the ears. The circumference of an average maize culm, 

 between the first and second nodes, in a dent or flint variety, will 

 be from three to four and one-half inches. Unlike most of the 

 plants of the grass family, the culm of maize is not hollow, the 

 interior being filled with a soft pith, which does not add mate- 



1 Miss. BuL 33, p. 75. 



