ORDER XXVIII.—MALVACEÆ.—THE MALLOW TRIBE.
All the plants belonging to Malvaceæ bear so much resemblance to each other, that this order may be considered a very natural one; and it is one very remarkable for the botanical construction of its flowers. In some respects it resembles Linaceæ, quite enough indeed to show clearly the chain by which they are so beautifully linked together; but in others, it differs so decidedly as to show how completely they are distinct. Fig. 119, which represents the
Fig. 119.—The flower, stamens, and pistils of the Althæa frutex. flower and seed-vessel of the Althæa frutex (Hibiscus syriacus), will serve to show the chief peculiarities of this order. The calyx consists of five sepals, below which is an involucrum of six or seven leaflets, which have the appearance of a second calyx. The corolla is cup-shaped, and consists of five petals, which are close together at the base, and this is peculiar to the genus Hibiscus. The capsule is round and somewhat convex, being nearly in the shape of what is called a batch-cake, as shown at c; it consists of five carpels grown together, each containing many seeds; and when ripe, it bursts naturally into five valves, each of which has a dissepiment down the centre. The filaments grow together very curiously, inclosing the styles, and forming a column in the centre of the flower, which is the distinguishing mark of the Malvaceæ. Some of the stamens are shorter than others, and as part of each filament is detached, the anthers form the fringe-like border to the column, shown at d. The anthers are kidney-shaped and one-celled, and this is another of the characteristics of the order; but the styles are terminated by five ball-shaped stigmas, like those of the Linum. There are many kinds of Hibiscus; but perhaps the best known are: H. rosa sinensis, the species which is so often represented in Chinese drawings, and the petals of which are so astringent, that they are said to be used in China by the men to black their shoes, and by the women to dye their hair; and the Bladder Ketmia (H. Trionum), which takes its English name from its inflated capsule. All the plants belonging to the order Malvaceæ have a central column, round which are placed numerous carpels, which grow together and form a many-celled capsule; and they all have kidney-shaped, one-celled anthers. They have also always an involucrum below the calyx, but this involucrum differs in the different genera. In the genus Malva, the involucrum consists of three leaflets, which in the common Mallow (Malva sylvestris) are oblong. The petals are wedge-shaped, and they are what botanists call auricled; that is, they are set so far apart at the base that light can be seen through them. The stamens are all of nearly the same height, and they form a kind of bunch round the styles, which are pointed. The capsule consists of a circle of woolly-looking carpels growing close together, but so as to be easily detached with a pin, and each fitting into a little groove in the receptacle, in which they are placed. As the seeds ripen, the involucrum falls off, but the large loose-looking calyx remains on. There is only one seed in each carpel; but as there are generally eleven carpels in each capsule, each seed-vessel contains this number of seeds. The leaves are lobed and toothed; and the whole plant is covered with long hairs, which are disposed in little star-like tufts.
The genus Malope closely resembles the Mallow; except that the petals are not wedge-shaped, and that it has a still larger calyx, the long sepals of which shroud the capsule as the involucre of the filbert does the nut. The involucrum is composed of three broad, heart-shaped leaflets, which remain on till the seed is ripe. The petals are also not so even along the margin; and the carpels are so disposed as to form a cone-shaped capsule, instead of a flat one.
The genus Lavatera has the leaflets of the involucre joined to the middle, so as to form a kind of three-cornered saucer below the capsule; and the capsule itself is completely covered with a part of the receptacle, which is dilated, and curved down over it. Lastly, the genus Althæa, the Marsh Mallow, has the involucrum cleft into six or nine divisions, and the carpels united into a globular capsule. The Hollyhock (A. rosea) belongs to this genus. Many other genera might be mentioned, but these will suffice to give my readers a general idea of the order, and of the points of difference which distinguish one genus from another. Among the exotic plants belonging to the order is the cotton tree (Gossypium herbaceum), the cotton being the woolly matter which envelops the seeds in the capsule. All the Malvaceæ abound in mucilage, and they all have woody fibre in their stems.
ORDER XXIX.—BOMBACEÆ.—THE SILK COTTON TREE TRIBE.
This order is closely allied to Malvaceæ, and it differs principally in the tube formed by the stamens being divided into five bundles near the top. It includes the Baobab, or Monkey-bread (Adansonia digitata), said to be the largest tree in the world; the Screw tree (Helicteres Isora), so named from its curiously-twisted fruit; Carolinia princeps; the Silk Cotton tree (Bombax Ceiba); and the Hand-plant (Cheirostemon platanoides),—this is the Hand-plant so named from the lobes of its leaves resembling fingers,—all stove plants in Britain.