512 BOTANY OF CROP PLANTS 



veins on the underside. Three to six inches is the common 

 length of Upland cotton leaves. 



Flowers. — Flower buds arise on fruiting branches. They 

 do not arise in the very axil of a leaf, but are distant 

 from it. There is a flower opposite a leaf at each node. 

 There is one flower in each bud. The flowers of Asiatic 

 species are often pendant. Upland cotton flowers are 3 to 

 4 inches across, white when they first open but turning pink 

 on the second day. Sea Island cotton flowers are usually 

 yellow, with a purple-red spot at the base of each petal. 



Involucre. — Each flower is subtended by an involucre (Fig. 

 211) composed of three bracts (sometimes four in cultivation) 

 united at the base. They are frequently large, dentate or 

 laciniate, sometimes entire. One of the bracts is often some- 

 what smaller than the other two which are equal in size. In 

 some cases bractlets may occur inside the involucre. They 

 alternate with the bracts. When two are present they stand 

 on either side of the smaller bract. This is the case in Upland 

 varieties in the United States. In certain Central American 

 varieties, they are sometimes six bractlets, a pair alternating 

 with each of the three bracts. 



Nectaries. — ^At the base of the outer surface of the bracts 

 are nectaries, in American sorts, but they are absent in all 

 cultivated Asiatic cottons. There are also inner involucral 

 glands in both American and Asiatic varieties. In the 

 former, these inner involucral glands are naked, with excep- 

 tion of Guatemalan cotton, while in Asiatic cottons they are 

 protected by a velvety covering of hairs. 



Calyx. — This is a very short, cup-shaped structure at 

 the base of the corolla. The rim of the cup is usually 

 five-lobed, the lobes being short and broad, or sometimes 

 rather long and pointed. In Egyptian cotton and some Asi- 

 atic species, the rim of the calyx is frequently very even, 



