530 HORTICULTURE, FORESTRY, FLORICULTURE 



having alternate stalked and lobed leaves. The flowers of upland 

 cotton are white or cream-colored on the first day, become reddish 

 on the second, and fall on the third, leaving a small boll enveloped 

 in the calyx. This boll develops until it reaches approximately the 

 size and shape of a hen's egg, when it splits into three to five cells, 

 liberating the numerous black seeds covered with the fibrous wood 

 which constitutes the cotton of commerce. Formerly cotton was 

 not grown north of the isothermal line 36, but under the influence 

 of phosphatic manures its cultivation in late years has been extended 

 several degrees beyond this line. It is most successfully cultivated 

 between 30 and 35 north latitude. Two periods in the life of this 

 plant may be distinguished. The first extends from the time of 

 planting, which in South Carolina is about the middle of April, to 

 the middle of summer. This is the time in which the plant makes 

 its growth of stalk and foliage and gathers nourishment, which will 

 later be stored up in the seed. During this period tropical condi- 

 tions are favorable, namely, moisture in the soil from frequent 

 rather than long-continued rain, high temperature with small daily 

 variation, plenty of sunshine, little wind, and a high relative hu- 

 midity of the atmosphere to reduce evaporation to a minimum. 

 During this period everything possible is done to prevent loss of 

 water from the soil ; grass and weeds are scrupulously excluded, and 

 the surface of the soil is frequently stirred to conserve the moisture 

 and increase the temperature of the soil. 



In the latter part of the season in South Carolina the temper- 

 ature rapidly falls and the rainfall diminishes. This is the fruiting 

 period of the cotton crop, when every effort should be made to pro- 

 duce seed rather than stalk and foliage. Every means is taken to 

 dry out the soil ; cultivation ceases and the soil is allowed to become 

 hard and compact to favor the evaporation of the moisture. It is be- 

 lieved that differences in moisture and temperature account for the 

 fact that the fine grades of sea-island cotton can be produced only 

 on the islands and in the country immediately adjoining the coast. 

 (U. S. E. S. B. 15.) 



Varieties of American Cotton. Two species of cotton are cul- 

 tivated in the United States. These are American Upland cotton 

 (Gossypiwn hirsutum L.) and Sea Island cotton (Gossypium bar- 

 badense L.). American Upland cotton, through misidentification, 

 has been referred by American authors to Gossypium herbaceum 

 L., but recent studies have shown conclusively that it is very distinct 

 from the Asiatic cottons, of which G. herbaceum is a representative 

 species. It is really more closely related to the Sea Island cotton. Both 

 species cultivated in this country origmatel in tropical America. 



Sea Island cotton (Gossypium barbadense L.) yields a very 

 fine, long, and silky staple, but can be grown commercially only in 

 a limited area near the coast of South Carolina, Georgia, and Flor- 

 ida. Partly because of this narrow geographical range but more on 

 account of the fact that breeders of Sea Island cotton have been 

 working toward one and the same end a still better staple the 

 species has not been split up into distinct types or groups of varieties. 



