COTTON STBUCTUBE 265 



sufficiently drained, the tap-root often turns and grows 

 in a horizontal direction on coming into contact with a 

 dense or undrained subsoil. 



Most of the lateral roots arise at points two to four 

 inches below the surface of the ground. Hence, deep 

 cultivation after the plant is several inches high results in 

 the destruction of many of the lateral roots. 



233. Leaves. — The leaves of cotton are alternate in 



position on the stem or branch. They vary somewhat in 



size and shape, even on the same plant. In American 



varieties, both of the short-staple and long-staple upland 



classes, the leaves are usually 



three-lobed, sometimes five- 



lobed. In these classes the 



spaces between lobes are usually 



shallow. Certain groups of vari- 



, . „ ,, 1 . 1 n T • 1 Fig- 126. — Cotton Leaves. 

 eties, chiefly the big-boU kmds, , ^ ^ „ ^ , , 



. , . a, upland ; b, Sea Island. 



have large leaves with quite 



shallow indentation, and short, broad lobes. Other groups, 



notably those of the King and Peterkin types, have smaller 



leaves with slenderer, more sharply pointed lobes. Between 



these groups are all gradations in size and shape of leaves. 



In Sea Island cotton the lobes are very slender and the 



indentations very deep (Fig. 126) . 



There are usually three (sometimes more) prominent 



veins or ribs in each leaf. On one or more of these on the 



under side of the leaf are glands that may easily be seen. 



The leaves of upland cotton are covered, especially on the 



lower side, with numerous short, inconspicuous hairs. 



234. Boll stems, or peduncles. — Connecting the flower 

 or boll with the branch is a short flower-stem (Figs. 121 and 



