514 BOTANY OF CROP PLANTS 



Pollination, Fertilization, and Development of Fruit. — 



Both cross- and self-fertilization may occur in cotton. Bees 

 may be necessary in those varieties in which the style is long 

 and brings the stigmas above the anthers. Floral nectaries, 

 at the base of the calyx on the inner side, are reached from 

 within the corolla by long-tongued bees and butterflies. 

 This is enabled by the failure of the petals to overlap at 

 the base, thus leaving gaps through which the insect may 

 protrwie its tongue. 



Ill lilfississippi the period required for maturity of bolls is 

 from forty-four to forty-six days. 



The seeds retain their attachment to the placenta until lint 

 begins to develop, when their connection is broken through 

 the absorption of the seed stalk, and the mechanical pressure 

 of growing lint. Hence, the seeds come to occupy a position 

 in the center of the cavity. Fiber begins to develop first at 

 the apex of the seed. 



Fruit. — The cotton fruit (Fig. 213) is a leathery capsule 

 locuhcidally dehiscent by three to five valves. The mature 

 capsule is called a "boll." It varies in shape: subglobose, 

 oval, or ovate-acuminate. The number of cells or "locks" 

 is three or four in Sea Island and Egyptian varieties, and four 

 or five in Upland sorts. 



Seeds. — There are numerous seeds in each "boll." Seeds 

 vary in shape: subglobose, ovate, or subovate. 



fiber. — The cotton fiber or hair is a simple extension of an 

 epidermal cell of the seed coat. As a rule, there are two kinds 

 of hairs on the seed: (i) long hairs — lint or commercial 

 fiber ("staple") and (2) short hairs or fuzz. The fuzz may 

 be white, green, or brown in color. Some varieties produce 

 no fuzz; hence when the seed is "ginned," it is left naked. 

 Fuzzy-seeded varieties usually possess an abundance of long 

 fibers. A high percentage of lint usually indicates small 



