Fig. 451.—The same in longitudinal section.
4. Ureneæ, have always only 5 carpels arranged in 1 whorl, with 1 ovule in each loculus, and the fruit a schizocarp, generally with nut-like fruitlets provided with warts and hooks; but in some they dehisce by 2 valves (capsule). They differ principally from the other groups in having twice as many stylar-branches as carpels; the staminal tube is naked at the point, blunt or 5 toothed.—The genera Urena, Pavonia, Malachra, Malvaviscus (with berry-like fruits) belong to this group.
II. Carpels arranged in a spherical head in five groups opposite to the petals.
5. Malopeæ, differ from all the others in having a large number of fruitlets arranged irregularly in a round head, and separating considerably from each other even before maturity; there is, however, only 1 style, divided into a corresponding number of branches (this condition may be considered to have arisen from the branching [dédoublement] of 5 carpels). Malope has 3 large, heart-shaped (Kitaibelia 6–9) epicalyx-leaves, united at the base. Palava has no epicalyx.
Pollination. The majority have protandrous flowers, and are pollinated by insects. Between the basal portions of the 5 petals, there are 5 nectaries, protected from the rain by hairs, e.g. in Malva silvestris. When the flower first opens the numerous anthers occupy the centre of the flower, and the still undeveloped stigmas are concealed in the staminal tube; in the next stage the anthers are withered and empty, and the stigmas protrude and assume their places (Fig. [452]). The large-flowered forms, it appears, are pollinated only by insects; but self-pollination takes place in small-flowered forms, as, for example, in Malva rotundifolia, in which the stylar-branches, twisting themselves, place the stigmas in between the undeveloped anthers.
Fig. 452.—Anoda hastata: a the bud just opened, the stigmas are concealed by the anthers; b fully opened flower in ♂-stage; the upper stamens are developed first, and then the others in descending order; the stylar-branches are now visible, and lie bent back on the staminal column; c all the stamens project upwards, and all the anthers are open, but the stylar-branches are still bent back; d the anthers are emptied and the filaments shrunk together, but the styles have now straightened themselves upwards, and the stigmas are in the receptive condition.
Distribution. 800 species (63 genera), most of which are natives of the Tropics, especially America. Althæa and some of the species of Malva are natives of the temperate regions of the Old World, the latter is also found in North America. Gossypium is tropical, no doubt especially Asiatic (G. herbaceum from India; G. arboreum from Upper Egypt). Cotton was introduced into Greece in the time of Herodotus, and was cultivated in America before the arrival of the Europeans.
Uses. Pungent and poisonous properties are entirely wanting; mucilage, on the other hand, is found in abundance in all parts of the plant. Medicinal: the root of Althæa officinalis, leaves and flowers of Malva-species (M. silvestris vulgaris and borealis) and Gossypium.—The seeds contain a large quantity of fatty oil, which is in some cases extracted (Cotton-seeds and others). The seed-hairs of the Cotton plant are the most important product of the order. The cultivated forms of Cotton belong to several species: G. barbadense, herbaceum, religiosum, arboreum (Nankin), hirsutum, and others. According to other botanists, there are only 3 species. Bast is obtained from e.g. Hibiscus cannabinus (Gambo-hemp, Africa), Paritium tiliaceum and Sida retusa. The fruits of certain species of Hibiscus (e.g. H. esculentus, from Tropical Africa) are used in tropical countries as a vegetable before they are ripe.—The colouring matter in the flowers of Althæa rosea, var. nigra, is used for colouring wines, and hence is extensively cultivated in certain parts of Europe.—Ethereal oils and sweet-scented flowers are rare; but several species possess a peculiar musk-like odour (Malva moschata, Hibiscus abelmoschus, and others).—Many are cultivated as ornamental plants on account of the large flowers, e.g. Hollyhock (A. rosea, etc.), Lavatera trimestris, Malope grandiflora and trifida, Malva-species, Hibiscus rosa sinensis, syriaca; Sphæralcea, etc.