MALVACE^ 511 



dormant, or the branches are extremely short or abortive." 

 The "zone of fruiting branches follows from about the 

 thirteenth node to the tip of the plant." 



Underground Stems. — The cotton plant may produce 

 underground stems. These arise from the same grooves from 

 which lateral roots come. At first, these subterranean shoots 

 are gall-like. Later, they attain various sizes. 



Leaves. — The leaves have a regular spiral arrangement. 

 The most common phyllotaxy in the cotton plant is three- 

 eighths. This is the normal arrangement in all pure strains 

 of Upland and Sea Island species and other natives of tropical 

 America that are related. It is pointed out that with "the 

 advance of acclimatization, the leaf arrangements are varied 

 by frequent examples of one-third and two-fifths spirals" 

 . . . Egyptian-Upland hybrid plantsmay have a one-third, 

 two-fifths, or five-thirteenths arrangement. The phyllo- 

 taxy is one-third in Asiatic cottons. However, when Asiatic 

 species are crossed, the hybrid plants may show a two-fifths 

 or three-eighths arrangement. Leaf arrangement is similar 

 on main stem and vegetative branches, but on fruiting 

 branches the leaves are in two alternate rows; this latter 

 condition is brought about by a twisting of the joints, each 

 internode being twisted in the opposite direction from the 

 adjacent. 



The leaves are petioled, stipulate, cordate as a rule, and 

 three- to seven-lobed, sometimes nine-lobed. Glands may 

 be present or absent on the leaves. When present, they 

 occur on the under side of the main ribs, about one-third of 

 the distance from the bases. 



The leaves on fruiting branches are often irregular in outline 

 and may have one or two glands. The leaves on vegetative 

 branches and on the main stem are regular in outline, and have 

 nectaries on the midrib and occasionally on the principal 



