494

STRUCTURE OF FLOWER OF ORCHIDEE.

anther-lobe, in an adherent state. Hence it follows, that the whole of this curious structure is to be regarded as a metamorphosed stamen; the channel down its middle marking the division of the anther-lobes, and the fissures on the two sides being analogous to the suture or split by which other anthers discharge their contents (§ 432,3). On each side of the base of the anther is a little roundish knob, which has something of a granular character, and which is to be regarded as a rudimentary stamen. At the foot of

the anther (lower part of B, Fig. 109) is a pale fleshy cup, one side of which is curved over its cavity; this is called the hood; and at the bottom of it is the viscid stigmatic surface. Here, then, we have the essential parts of the apparatus of fructification; only one style and one stigma, however, being developed; and these being adherent to one another. This latter character runs through the whole of the Orchideous group; as to the former, however, there is some variation. Thus, in the Cypripedium, or Lady's Slipper, a British Orchideous plant, the two little prominences just mentioned are fully developed into stamens, whilst the central one, which is here developed, is rudimentary; and in some other species, all three are occasionally present as complete

stamens.

695. There is much difficulty in understanding how the usual influence of the pollen on the stigma can be effected in these plants; since the pollen is not capable of being scattered as a fine powder through the air, as in other plants; and if it were to fall out in a mass, it would hardly touch the stigma. Some have supposed that absolute contact of the pollen with the stigma is not necessary, and have thought that the fertilizing influence could be communicated through the stalk of the pollen-mass. But this is now proved to be incorrect; as numerous experiments have shown that the contact is as necessary here as in other plants. It is difficult to perceive, however, in what manner it is naturally effected; and recourse has even been had to the supposition, that the agency of insects is necessary, in order to drag the pollen-masses from their case, and to diffuse their granules over the stigma.

On turning our attention to the general aspect of the

TUBEROUS ROOTS OF ORCHIDEE.

495

plant, we observe that it has a fleshy root consisting of two oval tubers, and of a number of succulent fibres; that its leaves, which have the simply-veined structure characteristic of Monocotyledons, spread from the surface or the ground; and that a straight flowerstalk is shot up from the midst of these. The stem and roots are connected with but one of the tubers; the other arises as a sort of lateral bud from this one. When the stem has unfolded its flowers and ripened its fruit, it dies down to the ground, and is succeeded in the ensuing season by a stem developed from the second tuber, the first being exhausted. This, again, serves for the vegetation of one season only, and a new tuber is formed as a bud, from which the next year's stem will be developed. Hence the species possessing this kind of root, always have a pair of tubercles, one shrivelling and in process of exhaustion, the other swelling and in process of completion. Sometimes the bottom of the stem, instead of forming a new tuber upon its side, pushes out a slender subterranean root-like runner, which, after growing to some length, is arrested and forms a tuber, from which the next stem is shot up; so that the plant may be said to change its place every year to a considerable distance. In many instances the tuber is formed above the ground, constituting what is known as the pseudo-bulb of the Orchideæ ; and its horizontal stem creeps along the surface as a rhizoma. In these cases, the structures are more permanent, the pseudo-bulbs acquiring a woody hardness, and continuing to send up stems; so that by their gradual multiplication, a large surface is often covered by a single plant.

697. It is remarkable that in a group so numerous as this,consisting as it does of nearly two thousand known species, and of probably as many more, which being buried in the depths of unexplored tropical forests, have not yet been described,—and extending over almost the whole habitual globe as far as the borders of the frozen zone,—there should be so few species possessed of properties that make them in any way useful to man. It often happens that the most powerful virtues, or the most deadly poisons, are hidden beneath a mean and insignificant exterior; whilst those productions of nature which charm the eye with their

496 ORCHIS TRIBE; VANILLA, SALEP.--GINGER TRIBE. beauty, and delight the senses with their perfume, have the least relation with the wants of mankind. So it appears to be in this instance. The aromatic substance called Vanilla, which is sometimes used as an ingredient in chocolate, also to flavour sweet dishes, and to perfume snuff, is the succulent fruit of an Orchideous plant, which, in the West Indies, creeps over trees and walls like ivy. A nutritive substance termed Salep, somewhat resembling Arrow-root or Sago, is obtained from the tubers of a species which grows in Turkey and Persia, where it is highly · esteemed. It used to be sold at the.corners of the streets in London, and was a favourite drink with porters, coal-heavers, and other hard-working people, by whom it was considered very strengthening; and the comparative disuse in which it has fallen is perhaps to be regretted. It is said to contain a greater amount of nutriment in the same bulk, than any other vegetable substance; and for this reason it is much employed by travellers who have to carry their supplies with them into deserts and uninhabited countries. So high a nutritive power has been assigned to it, that it has been asserted that one ounce of Salep, boiled with an equal quantity of the stiff glue or animal jelly known as portable soup, in two quarts of water, will suffice for the daily nourishment of an able-bodied man. Some of the South American species contain a viscid substance, which, when separated by boiling, serves as a sort of glue which is used by the Brazilians for sticking together their skins of leather. There is scarcely any other way in which this order is of any direct utility to man.

698. Of the next order, SCITAMINEE, the Ginger tribe, there are no British representatives; but its structure will be very easily comprehended, as we now return to a nearly regular type of structure. They are all aromatic herbaceous plants, only coming to perfection between the tropics; and they are nearly all characterised by possessing a rhizoma, which creeps along the ground, and from the sides of which the leaf and flower-stalks are annually shot up. The flowers arise from expanded scaly bodies, which are clusters of bracts, one for the protection of each pair of buds. The ovarium, as in the Orchideæ, is inferior; and the calyx, which arises

ORDER SCITAMINEE, OR GINGER TRIBE.

497

from its summit, is tubular, and is formed by three sepals adherent nearly to their points. Within this are two whorls of leafy organs,

Fig. 110. Ginger Plant.

the outer of which is to be regarded as the true corolla, whilst the inner one consists of transformed stamens. In each whorl there are three segments; those of the outer whorl, or petals, are partly adherent SO as to form a tube, and are nearly equal,-one being sometimes larger than the rest or differently shaped, so as to show some affinity with the Orchideæ. Of the inner whorl of transformed stamens, one is usually very much enlarged, like

the labellum of Orchidea, whilst the others are almost undeveloped. Within this whorl, there are three distinct stamens, of which, however, only one usually bears pollen; but this is quite distinct from the pistil. The ovarium is usually three-celled, though sometimes imperfectly so, the partitions not being complete, so as to approach that of the Orchidea in character. The style is long and thread-like, dilated into an expanded stigma at the top. The fruit is generally a three-celled capsule.

699. These plants are generally objects of great beauty, either on account of the high degree of development of the coloured parts of the flower itself, or because of the rich and glowing hues of the bracts. They are, however, principally valued on account of the aromatic and stimulating properties, which the rhizoma of most

498

GINGER; TURMERIC; CARDAMOM.

species possesses. This is best known in the common Ginger, which is produced from a plant originally found in the south-east of Asia and the adjoining islands, but early transplanted to America and the West Indies, where it has been cultivated with great success, the Jamaica Ginger being esteemed much superior in quality to the East Indian. The dry Ginger of commerce is distinguished into white and black; but the difference of colour wholly depends upon the mode of preparation. For both these kinds, the rhizoma is allowed to remain, until the annual stalks are withered : the best and soundest roots being selected for white ginger, they are scraped clean and dried carefully in the sun; but the others are merely scalded and then dried. When a preserve is to be made of the root-stocks, they are dug up whilst in sap, the stalks not being then more than five or six inches long. For this purpose, the young roots are scalded, then washed in cold water, and afterwards carefully peeled. They are then soaked for three or four days, during which the water is frequently changed; and being subsequently put into jars, a weak syrup is poured over them, which is afterwards exchanged for a stronger one, and so on for two or three times. The manner of cultivating ginger is extremely simple, requiring little care; it is propagated with as much ease, and nearly in the same manner, as potatoes are in Great Britain. Other species of this tribe are valued for their spicy qualities; such is the Turmeric Plant, formerly mentioned as yielding a beautiful yellow dye (397), of which the powdered rootstock is one of the constant ingredients with ginger, cardamoms, and other spices, in the celebrated curry-powders of the East Indies. The seeds also of some species, as the Cardamom, are aromatic, and are employed in medicine as cordials. The rhizoma of almost every plant in this order contains a large quantity of starch, which might be employed in the same manner as Arrowroot; but it is difficult to separate this in such a manner, as to free it from the pungent and resinous secretions with which it is intermixed. 700. The order MARANTACEE or Arrow-root tribe is so nearly allied to Scitamineæ, that some Botanists have associated them.