spin into thread, and for this reason, amongst others, are very
considerably less important as textile fibres. The chief of these
silk cottons is kapok, consisting of the hairs borne on the interior
of the pods (but not attached to the seeds) of Eriodendron
anfractuosum, the silk cotton tree, a member of the Bombacaceae,
an order very closely allied to the Malvaceae.
 |
| From Strasburger’s Lehrbuch der Botanik, by permission of Gustav Fischer. Fig. 1.—Seed-hairs of the Cotton, Gossypium herbaceum. A, Part of seed-coat with hairs; B1, insertion and lower part; B2, middle part; and B3, upper part of a hair. |
Classification.—Considerable difficulty is encountered in attempting to draw up a botanical classification of the species of Gossypium. Several are only known in cultivation, and we have but little knowledge of the wild parent forms from which they have descended. During the periods the cottons have been cultivated, selection, conscious or unconscious, has been carried on, resulting in the raising, from the same stock probably, in different places, of well-marked forms, which, in the absence of the history of their origin, might be regarded as different species. Then again, during at least the last four centuries, cotton plants have been distributed from one country to another, only to render still more difficult any attempt to establish definitely the origin of the varieties now grown. Under these circumstances it is not surprising to find that those who have paid attention to the botany of the cottons differ greatly in the number of species they recognize. Linnaeus described five or six species, de Candolle thirteen. Of the two Italian botanists who in comparatively recent years have monographed the group, Parlatore (Le Specie dei cotoni, 1866) recognizes seven species, whilst Todaro (Relazione sulla culta dei cotoni, 1877–1878) describes over fifty species: many of these, however, are of but little economic importance, and, in spite of the difficulties mentioned above, it is possible for practical purposes to divide the commercially important plants into five species, placing these in two groups according to the character of the hairs borne on the seeds. Sir G. Watt’s exhaustive work on Wild and Cultivated Cotton Plants of the World (1907) is the latest authority on the subject; and his views on some debated points have been incorporated in the following account.
A seed of “Sea Island cotton” is covered with long hairs only, which are readily pulled off, leaving the comparatively small black seed quite clean or with only a slight fuzz at the end, whereas a seed of “Upland” or ordinary American cotton bears both long and short hairs; the former are fairly easily detached (less easily, however, than in Sea Island cotton), whilst the latter adhere very firmly, so that when the long hairs are pulled off the seed remains completely covered with a short fuzz. This is also the case with the ordinary Indian and African cottons. There remains one other important group, the so-called “kidney” cottons in which there are only long hairs, and the seed easily comes away clean as with “Sea Island,” but, instead of each seed being separate, the whole group in each of the three compartments of the capsule is firmly united together in a more or less kidney-shaped mass. Starting with this as the basis of classification, we can construct the following key, the remaining principal points of difference being indicated in their proper places:—
| i. Seeds covered with long hairs only, flowers yellow, turning to red. | ||||
| A. Seeds separate. | ||||
| Country of origin, Tropical America—(1) G. barbadense, L. | ||||
| B. Seeds of each loculus united. | ||||
| Country of origin, S. America—(2) G. brasiliense, Macf. | ||||
| ii. Seeds covered with long and short hairs. | ||||
| A. Flowers yellow or white, turning to red. | |||
| | a. | Leaves 3 to 5 lobed, often large. | |
| Flowers white. | |||
| Country of origin, Mexico—(3) G. hirsutum, L. | |||
| b. | Leaves 3 to 5, seldom 7 lobed. Small. | ||
| Flowers yellow. | |||
| Country of origin, India—(4) G. herbaceum, L. | |||
| B. Flowers purple or red. Leaves 3 to 7 lobed. | |||
| Place of origin, Old World—(5) G. arboreum, L. | |||
1. G. barbadense, Linn. This plant, known only in cultivation, is usually regarded as native to the West Indies. Watt regards it as closely allied to G. vitifolium, and considers the modern stock a hybrid, and probably not indigenous to the West Indies. He classifies the modern high-class Sea Island cottons as G. barbadense, var. maritima. Whatever may be its true botanical name it is the plant known in commerce as “Sea Island” cotton, owing to its introduction and successful cultivation in the Sea Islands and the coastal districts of South Carolina, Georgia and Florida. It yields the most valuable of all cottons, the hairs being long, fine and silky, and ranging in length from 38 to 212 in. By careful selection (the methods of which are described below) in the United States, the quality of the product was much improved, and on the recent revival of the cotton industry in the West Indies American “Sea Island” seed was introduced back again to the original home of the species.
Egyptian cotton is usually regarded as being derived from the same species. Watt considers many of the Egyptian cottons to be races or hybrids of G. peruvianum, Cav. Egyptian cotton in length of staple is intermediate between average Sea Island and average Upland. It has, however, certain characteristics which cause it to be in demand even in the United States, where during recent years Egyptian cotton has comprised about 80% of all the “foreign” cottons imported. These special qualities are its fineness, strength, elasticity and great natural twist, which combined enable it to make very fine, strong yarns, suited to the manufacture of the better qualities of hosiery, for mixing with silk and wool, for making lace, &c. It also mercerizes very well. The principal varieties of Egyptian cotton are: Mitafifi, the best-known and most extensively grown, hardy and but little affected by climatic variation. It is usually regarded as the standard Egyptian cotton; the lint is yellowish brown, the seeds black and almost smooth, usually with a little tuft of short green hairs at the ends. Abassi, a variety comparatively recently obtained by selection. The lint is pure white, very fine and silky, but not so strong as Mitafifi cotton. Yannovitch, a variety known since about 1897, yields the finest and most silky lint of the white Egyptian cottons. Bamia, yielding a brown lint, very similar to Mitafifi, but slightly less valuable. Ashmouni, a variety principally cultivated in Upper Egypt. The lint is brown and generally resembles Mitafifi but is less valuable.
Other varieties are Zifiri, Hamouli and Gallini, all of minor importance.
2. G. brasiliense, Macf. (G. peruvianum, Engler), or kidney cotton. Amongst the varieties of cotton which are derived from this species appear to be Pernambuco, Maranham, Ceara, Aracaty and Maceio cottons. The fibre is generally white, somewhat harsh and wiry, and especially adapted for mixing with wool. The staple varies in length from 1 to about 112 in.
3. G. hirsutum, Linn. Although G. barbadense yields the most valuable cotton, G. hirsutum is the most important cotton-yielding plant, being the source of American cotton, i.e. Upland, Georgia, New Orleans and Texas varieties. The staple varies usually in length between 34 and 114 in. According to Watt there are many hybrids in American cottons between G. hirsutum and G. mexicanum.
