One of the most remarkable botanical discoveries of modern days is that of a very curious and anomalous genus of plants, named by Dr. Hooker Welwitschia in honor of its discoverer. Dr. Frederic Welwitsch, who first noticed this singular plant in a letter to Sir William Hooker, dated August, 1860. "I have been assured," says Dr. Hooker in his valuable memoir of this plant, "by those who remember it, that since the discovery of the Rafflesia Arnoldii, no vegetable production has excited so great an interest as the subject of the present memoir." We well remember this singular plant, having seen a specimen in the Kew Herbarium soon after its arrival in this country. The following is Dr. Hooker's account of its appearance and prominent characters:
"The Welwitschia is a woody plant, said to attain a century in duration, with an obconic trunk about two feet long, of which a few inches rise [{194}] above the soil, presenting the appearance of a flat, two-lobed depressed mass, sometimes (according to Dr. Welwitsch) attaining fourteen feet in circumference (!) and looking like a round table. When full grown, it is dark brown, hard, and cracked over the whole surface (much like the burnt crust of a loaf of bread); the lower portion forms a stout tap-root, buried in the soil and branching downward at the end. From deep grooves in the circumference of the depressed mass two enormous leaves are given off, each six feet long when full grown, one corresponding to each lobe. These are quite flat, linear, very leathery, and split to the base into innumerable thongs that lie curling upon the surface of the soil. Its discoverer describes these same two leaves as being present from the earliest condition of the plant, and assures me that they are in fact developed from the two cotyledons of the seed, and are persistent, being replaced by no others. From the circumference of the tabular mass, above but close to the insertion of the leaves, spring stout dichotomously branched cymes, nearly a foot high, bearing small erect scarlet cones, which eventually become oblong and attain the size of those of the common spruce fir. The scales of the cones are very closely imbricated, and contain when young and still very small solitary flowers, which in some cases are hermaphrodite (structurally but not functionally), in others female."
After describing these flowers in botanical terms. Dr. Hooker adds, "The mature cone is tetragonous, and contains a broadly winged scale. Its discoverer observes that the whole plant exudes a resin, and that it is called 'tumbo' by the natives. It inhabits the elevated sandy plateau near Cape Negro (lat 14° 40' S. to 23° S.) on the south-west coast of Africa." Dr. Hooker regards the Welwitschia as "the only perennial flowering-plant which at no period has other vegetative organs than those proper to the embryo itself,—the main axis being represented by the radicle, which becomes a gigantic caulicle and develops a root from its base, and inflorescences from its plumulary end, and the leaves being the two cotyledons in a very highly developed and specialized condition." [Footnote 29]
[Footnote 29: "Transactions of the Linnean Society," vol. xxiv., part i.]
Few countries present more objects of interest to the naturalist than the island of Madagascar, amongst the botanical treasures of which island the water yam or lace-leaf (Ouviranidra fenestralis) claims especial notice. This beautiful and singular plant, which belongs to the natural order Naiadaceae, was first made known to the scientific world by du Petit Thouars in 1822. Horticulturists are indebted to Mr. Ellis, the well-known author of "Polynesian Researches," for the introduction of this singular plant into England, specimens of which may be seen in the Royal Gardens at Kew and elsewhere:
"This plant," says Mr. Ellis, "is not only extremely curious, but also very valuable to the natives, who, at certain seasons of the year, gather it as an article of food—the fleshy root when cooked yielding a farinaceous substance resembling the yam. Hence its native name, ouvirandrano, literally, yam of the water;—ouvi in the Malagasy and Polynesian languages signifying yam, and rano in the former and some of the latter signifying water. The ouvirandra is not only a rare and curious, but a singularly beautiful plant, both in structure and color. From the several crowns of the branching root, growing often a foot or more deep in the water, a number of graceful leaves, nine or ten inches long and two or three inches wide, spread out horizontally just beneath the surface of the water. The flower-stalks rise from the centre of the leaves, and the branching or forked flower is curious; but the structure of the leaf is peculiarly so, and seems like a living fibrous skeleton rather than an entire leaf. The [{195}] longitudinal fibres extend in curved lined along its entire length, and are united by thread-like fibres or veins, crossing them at right angles from side to side, at a short distance from each other. The whole leaf looks as if composed of fine tendrils, wrought after a most regular pattern, so as to resemble a piece of bright-green lace or open needlework. Each leaf rises from the crown on the root like a short delicate-looking pale green or yellow fibre; gradually unfolding its feathery-looking sides and increasing its size as it spreads beneath the water. The leaves in their several stages of growth pass through almost every gradation of color, from a pale yellow to a dark olive-green, becoming brown or even black before they finally decay; air-bubbles of considerable size frequently appearing under the full-formed and healthy leaves. It is scarcely possible to imagine any object of the kind more attractive and beautiful than a full-grown specimen of this plant, with its dark green leaves forming the limit of a circle two or three feet in diameter, and in the transparent water within that circle presenting leaves in every stage of development, both as to color and size. Nor is it the least curious to notice that these slender and fragile structures, apparently not more substantial than the gossamer and flexible as a feather, still possess a tenacity and wiriness which allow the delicate leaf to be raised by the hand to the surface of the water without injury."
No natural order of plants has created or continues to create a greater degree of interest amongst travellers and botanists than the Orchidaceae, of which more than three thousand species have been described; the anomalous structure of their reproductory parts, the singularity in form of the floral envelopes, the grotesque resemblance which many kinds bear to some object or other of the animal world, the rarity, beauty, and delicious fragrance of some forms—all combine to render these plants of great value and interest. As inhabitants of hot and damp localities, orchids are in general epiphytes, as in the Brazilian forests, in the lower portions of the Himalayan mountains, and in the islands of the Indian archipelago; when they occur in temperate regions they are terrestrial in their mode of growth; in extremely dry or cold climates, orchidaceous plants are unknown. Two rare and beautiful epiphytal orchids, the Angraecum sesquipedale and A. superbum, were obtained by Mr. Ellis in Madagascar and Mauritius, and introduced into this country. Of the former, the largest flowered of all the orchids, Dr. Lindley has given the following description:
"The plant forms a stem about eighteen inches high, covered with long leathery leaves in two ranks, like Venda tricolor and its allies; but they have a much more beautiful appearance, owing to a drooping habit, and a delicate bloom which clothes their surface. From the axils of the uppermost of these leaves appear short stiff flower-stalks, each bearing three and sometimes five flowers, extending seven inches in breadth and the same in height. They are furnished with a firm, curved, tapering, tail-like spur, about fourteen inches long. When first open, the flower is slightly tinged with green except the tip, which is almost pure white; after a short time the green disappears, and the whole surface acquires the softest waxy texture and perfect whiteness. In this condition they remain, preserving all their delicate beauty, for more than five weeks. Even before they expand, the greenish buds, which are three inches long, have a very noble appearance."
To the scientific naturalist few subjects are more full of deep interest than the question of the geographical distribution of animals. Dr. Sclater, the active secretary of the Zoological Society of London, has contributed an instructive paper, "On the Mammals of Madagascar," to the second, number [{196}] of the "Quarterly Journal of Science," from which we gather the following facts: As a general rule, it is found that the faunae and florae of such countries as are most nearly contiguous do most nearly resemble one another, while, on the other hand, those tracts of land which are furthest asunder are inhabited by most different forms of animal and vegetable life. Now, Madagascar, with the Mascarene islands, is a strange exception to the rule; for the forms of mammalia which are found in these islands are very different from the forms which occur in the contiguous coast of Africa, although the channel between Madagascar and the continent is in one place not more than 200 miles: "The numerous mammals of the orders Ruminantia, Pachydermata, and Proboscidea, so characteristic of the Ethiopian fauna, are entirely absent from Madagascar. The same is the case with the larger species of carnivora which are found throughout the African continent, but do not extend into Madagascar. Again, the highly organized types of Quadrumana which prevail in the forests of the mainland are utterly wanting in the neighboring island; their place being there occupied by several genera of the inferior family of Lemurs," Dr. Sclater shows that this anomaly is not confined to the orders already enumerated, but that similar irregularities prevail to a greater or lesser extent in every part of the mammalian series, and that, in short, the anomalies presented to us of the forms of life prevalent in the island of Madagascar "are so striking that claims have been put forward in its favor to be considered as a distinct primary geographical region of the earth." Dr. Sclater also draws attention to the very curious fact, "quite unparalleled, as far as is hitherto known, in any other fauna, that nearly two-thirds of the whole number of known species of the mammals of this island are members of one peculiar group of Quadrumana." The family of Lemuridae contains no less than eight generic types, all different from those found in Africa and India, although this group is also represented in Africa by the abnormal form Perodicticus, and in India by Nycticebus and Loris, two allied genera. The celebrated Aye Aye (Chiromys Madagascariensis), a specimen of which anomalous animal is at present in the new monkey-house in the Zoological Society's Gardens, Regent's Park, is considered by Prof. Owen to be more nearly allied to some of the African Galagos than to any other form of animal. Of insectivora, the genera Centetes, Ericulus, and Echinogale, small animals resembling hedge-hogs in outward appearance, are thought to be most nearly allied to an American genus. From the anomalies in the mammalian fauna of this island. Dr. Sclater arrives at the following deductions, which, however, as they are based upon the hypothesis of the derivative origin of species, cannot at present be deemed altogether conclusive:
"1. Madagascar has never been connected with Africa, as it at present exists. This would seem probable from the absence of certain all-pervading Ethiopian types in Madagascar, such as Antelope, Hippopotamus Felis, etc. But, on the other hand, the presence of Lemurs in Africa renders it certain that Africa as it at present exists, contains land that once formed part of Madagascar.
"2. Madagascar and the Mascarene islands (which are universally acknowledged to belong to the same category) must have remained for a long epoch separated from every other part of the globe, in order to have acquired the many peculiarities now exhibited in their mammal fauna—e.g., Lemur, Chiromys, Eupleres, Centetes, etc.—to be elaborated by the gradual modification of pre-existing forms.
"3. Some land-connection must have existed in former ages between Madagascar and India, whereon the original stock, whence the present Lemuridae of Africa, Madagascar, and India, are descended, flourished.
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"4. It must be likewise allowed that some sort of connection must also have existed between Madagascar and land which now forms part of the new world—in order to permit the derivation of the Centetinae from a common stock with the Solenodon, and to account for the fact that the Lemuridae, as a body, are certainly more nearly allied to the weaker forms of American monkeys than to any of the Simiidae of the old world.
"The anomalies of the mammal fauna of Madagascar can best be explained by supposing that, anterior to the existence of Africa in its present shape, a large continent occupied parts of the Atlantic and Indian oceans, stretching out toward (what is now) America on the west, and to India and its islands on the east; that this continent was broken up into islands, of which some became amalgamated with the present continent of Africa, and some possibly with what is now Asia—and that in Madagascar and the Mascarene islands we have existing relics of this great continent."