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Marine botany exhibits a similar diversity of species in different temperatures and localities of the ocean. The Polar Atlantic, the West Indian seas, the Indian Ocean and its gulfs, the eastern shores of South America, the coasts of Australasia, the Mediterranean and Red seas, have each peculiar kinds of algae, or sea-weed, belonging to them, though some marine productions take a very wide range, and appear to be universally diffused. The genus fucus, which grows up to the surface from deeply sunk rocks, forming immense beds, which act as natural breakwaters, and appear like extensively inundated meadows, through which ships with difficulty can make their way, is found from the extreme southern islets near Cape Horn, along the whole western coast of South America, and in the tropical Atlantic Ocean. It is abundant in the northerly regions of the deep. This plant has already been mentioned as remarkable for the enormous length of its stems, in some cases reaching to three hundred and sixty feet. It is a striking example, also, of rapid growth. Mr. Stephenson found that a rock uncovered only at spring-tides, which had been chiselled smooth in November, was thickly covered with fucus digitatus two feet in length, and fucus esculentus six feet, in the following May, within six months afterwards. Some terrestrial plants, likewise, are extensively diffused, and adapt themselves to every variety of climate. The Samolus valerandi, a flowering marsh plant, occurs all over the globe, associated with the birches of the frozen north, and with the palms of the burning tropics.

But climate only suffices very partially to explain the phenomena of vegetable distribution; for under the same, or corresponding parallels of latitude, at the same elevations above the level of the sea, and upon kindred soils, we find totally distinct genera, and different species. The genus erica, or the common heath, seems to be exclusively confined to one side of our planet. It is chiefly to be found in a narrow longitudinal zone, extending from the northern parts of Europe to the Cape of Good Hope; for it rarely occurs in Asia, and of the 300 known species only one belongs to America. "Large commons without heaths," says Sir C. Lyell, speaking of his first transatlantic impressions, in the neighbourhood of Boston, "reminded me of the singular fact that no species of heath is indigenous on the American continent." On the other hand, the cactus family belongs as exclusively to the New World as the heaths to the Old. The beautiful and fragrant rose-tree appears to be entirely wanting as a native plant in South America. and throughout the southern hemisphere; and in general, comparing the vegetation of the two continents, where the same genera recur, the species are not identical. Humboldt found upon the lofty mountains of equinoctial America, where the climate corresponds with that of the temperate zone, plantains, valerians, arenarias, ranunculuses, medlars, oaks, and pines, which, from their physiognomy, might be confounded with those of Europe, but they were all specifically different. The plants of Australasia, with very few exceptions, are different to those of the rest of the world; and of sixty-one native species, in the little island of St. Helena, only two or three are to be found in any other part of the globe. In some instances, upon travelling across a ridge of mountains, without any change of latitude, the vegetation is found quite different on the one side from the other. Nothing can be more striking than the contrast between the vegetation of the eastern and western sides of the chain of the Rocky Mountains. On the eastern side azaleas, rhododendrons, magnolias, with a variety of oaks and elms, form the principal features of the landscape; but beyond the ridge, most of these genera entirely disappear, and the giant pine becomes the chief object in view. Starting in an easterly direction through the northern parts of the Old World, we gradually lose the oak, the wild-nut, and the appletree, so common in Europe, upon crossing the Uralian mountains, and they cease to be met with beyond the banks of the Tobol; but in the eastern parts of Asia, on the banks of the Argouan, the two former occur anew, and the last re-appears in the Aleutian isles.

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There are multitudes of plants of a completely insulated growth flourishing spontaneously in a particular spot, and nowhere else. Examples occur upon the volcano of Guadaloupe, the Table Mountain of the Cape, and upon some sites of New Zealand; but the most remarkable case of this kind is that of the cedar of Lebanon, which has never been found indigenous in any other locality. From the earliest times the cedars of Lebanon have been celebrated. Their timber was largely used in some of the most famous structures of the ancients, and was highly prized on account of its durability; for though not equal to the oak in absolute wear, it is so bitter that no insect will touch it. When Solomon built his temple, he sent to Hiram, the lord-paramount of Lebanon, to procure the necessary quantity of cedar-wood for the structure; and the thirty thousand axes of the King of Israel must have deprived the heights of some of their noblest trees. Very few of the ancient stock now exist-whether owing to similar ravages, or to some change in the climate, it is impossible to determine. When Ballonius visited them in the year

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1550, there were twenty-eight of the old race remaining. In 1575 Rauwolf found twenty-four; in 1680 Dandini found twenty-three; in 1738 Pococke counted fifteen; in 1811 Burckhardt could only number eleven; Dr. Richardson in 1828, and Lamartine in 1832, speak of only seven. The age of these patriarchs of the forest has been variously estimated. The inhabitants firmly believe them to be the remains of that identical forest which flourished in the time of Solomon. Lamartine supposes it a fair presumption, from their size and appearance, that they go back to biblical times. It is certain that they were regarded as very ancient several centuries ago; nor is it unlikely that they are the surviving relics of a second generation since the time of the Jewish king. The cedar, full grown, with its upward inclining branches, is one of the most majestic and beautiful of the productions of the vegetable kingdom. The Arabs regard this inclination as a sign of intelligence, answering to instinct in animals, and reason in man; and it is asserted that this upward turning of the branch is always greater previous to the descent of the snow, as if the tree anticipated, and prepared to receive, the coming burden.

"It was a cedar tree

That woke him from the deadly drowsiness;

The broad round-spreading branches, when they felt

The snow, rose upward in a point to heaven,

And, standing in their strength erect,

Defied the baffled storm."

Various magnificent specimens of the cedar of Lebanon have been reared in England, but it has never been found growing wild apart from the Syrian mountains.

Owing to the exclusive confinement of individual families of plants to particular localities, or their predominance there, the globe has been divided into a series of botanical habitations, regions, or provinces, which are named after the most remarkable feature of their vegetation, or characterised by the geographical terms commonly applied to the districts. In the arrangement of Professor Schouw both methods are adopted, but the latter only where a distinct botanical province is surmised, without a sufficient acquaintance with its productions being possessed to denominate it after those which are most predominant. There are about fifty botanical regions noticed by De Candolle; forty-eight by Mr. Hinds; and twenty-two by Professor Schouw. From the latter the following arrangement is derived :

1. The region of saxifrages and mosses, or the alpine arctic flora. This region is characterised by the abundance of mosses and lichens; by the presence of the saxifrages, and gentians, chickweed tribe, sedges, willows; by the total absence of tropical families, and a marked decrease of the forms peculiar to the temperate zone, of the forests of firs and birches, and an absence of other forests. It is also distinguished by the small number of annual plants, the prevalence of perennial species, and by a greater liveliness in their simple colours. The region is divided into two provinces: 1. The province of the Carices, or the Arctic Flora, which comprehends all the countries within the polar circle, with some parts of America, Europe, and Asia, which are to the south of it; more especially Lapland, the north of Russia, Siberia, Kamschatka, New Britain, Canada, Labrador, Greenland, and the mountains of Scotland and Scandinavia. The Laplander combs and dresses some species of carex, as we do flax, and in winter stuffs his shoes and gloves with it, as a protection against the extreme cold of the climate. 2. The province of Primroses and Rampions, or the Alpine Flora of the south of Europe, which embraces the flora of the Pyrenees, Switzerland, the Tyrol, Savoy, the Apennines, the mountains of Greece, and probably the Spanish mountains.

2. The region of the umbelliferous and cruciferous plants, to which the hemlock, parsley, wall-flower, and cresses belong. These tribes are here in much greater number than in any other region. Roses, crowfoots, amentaceous and coniferous plants are also very numerous. The abundance of carices, and the fall of the leaves of almost all the trees during winter, form, also, chief features of this division. It may be separated into two distinct provinces:-1. The province of the cichoracea, including the sowthistle, dandelion, and lettuce, which embraces all the north of Europe, not comprehended in the preceding region, namely, Britain, the north of France, the Netherlands, Germany, Denmark, Poland, Hungary, and the greater part of European Russia. 2. The province of the astragali, and cynarocephala, to which the milkvetch, burdock, and thistle belong, which includes a part of Asiatic Russia, and the countries about the Caucasian mountains.

3. The region of the labiata, and caryophilla, to which the pink, catch-fly, and sandworts belong, or the Mediterranean flora. It is distinguished by the abundance of the plants belonging to these two orders. Some tropical families are also met with, such as palms, laurels, arums, plants yielding balsam and turpentine, grasses belonging to the

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