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SOUTH AFRICA WHICH ARE DUE TO THE PRE-
VAILING WINDS.

BY R. MARLOTH, PH.D., M.A.

In tracing the relations between the climate of a country and its vegetation, it is often thought sufficient to discuss the temperature, i.e., the mean for the year or the months with the extremes of heat and cold, and the rainfall, viz., its total amount and the distribution over the different seasons. One calls the climate of Eastern South Africa the reverse of that of the West simply because their rainy seasons are opposite to each other.

It is, consequently, often overlooked, that climate with regard to vegetation includes several other factors, which have a considerable influence on the structure and aspect of plants, and that some of these are capable of modifying the effect of the two principal constituents of the climate to a large extent. One of these important factors is the relative humidity of the air, which does not necessarily go parallel to the rainfall. Further, the annual and daily amount of sunshine, for light is as necessary to the living plant as heat and water. One of the reasons why many Cape plants do not thrive in English conservatories is the curtailing of the supply of light to which they are accustomed.

Quite as important, however, as these factors, is the wind, if it does not even exceed their influence considerably.

The various ways in which the wind affects the vegetation of South Africa may be grouped under three heads :

I.

2.

3.

Mechanical effects.

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The exhausting action, which it exerts on the leaves and growing points of plants.

The supplying of moisture to the vegetation of some of our mountains by means of the clouds which accompany certain kinds of wind.

Everybody is familiar with the shorn shrubs and dwarf trees along the seashore. The wind, often charged with salt spray or sand, destroys every leaf or twig, which projects above the sheltering rocks, and gives a slanting face to the top of the shrubs on the windward side. On the shores of False Bay, and even a mile or two inland, such wedge-shaped bushes are very common; but, of course, also everywhere else along the coast right up to Algoa Bay and East London. Some of them are as sharply defined as if they had been kept constantly under the gardener's scissors.

In other cases the pressure of the wind has forced the trees over to leeward. One may see whole rows of pines or eucalypts at Salt River and other equally windy places, which are leaning over to a considerable extent. Even groves of silver trees exhibit occasionally the same phenomenon, and in the coastbelt near East London stand thousands of dwarfed mimosa trees leaning over in the same direction, with a crown that is as flat as a table, all branches having been shorn down to the same plane by the sea wind.

The exhausting and destructive effect, which strong winds exert on the leaves of plants, is well seen after a South-East storm. The oaks and other soft-leaved plants look as if they had been scorched on the weather side. This is due to the enormous increase in the transpiration of the leaves, produced by the air which rushes past their surface with great velocity. As the supply of water from the roots cannot replace the loss with sufficient speed, the cells of the leaves are killed and the leaves dry up. Many introduced shrubs and trees suffer in a similar way, and many kinds cannot be reared in exposed situations, as e.g., chestnuts and horse-chestnuts, but do thrive in sheltered nooks and valleys.

Much

Quite different is the appearance of the indigenous trees of the Cape, even after the severest storm. While oaks are scorched, and even eucalypts and pepper trees (Schinus molle) seriously damaged, the olives and proteas show no sign of injury to their foliage. less do this the hundreds of smaller shrubs and shrublets, which form the plant covering of the South-Western districts. The explanation is simple. Their leaves are of tough and leathery texture, they are trained to such extreme conditions; in fact, the wind has, to some extent at least, been instrumental in gradually producing them by a kind of natural selection. Almost all shrubby plants of the SouthWestern districts possess such leathery leaves, hence this part of South Africa is designated by ecologists as one of the typical regions of sclerophyllous plants.

It must not be thought that the wind is the only cause of this special feature in our vegetation, but it has certainly had a considerable share in its production.

The influence of this action of the wind is even more conspicuous in other cases. In localities, which are regularly exposed to strong winds from the same direction, one finds the trees often without branches on the weather side. Near Cape Town there are many pines on the slopes of the Devil's Peak with a perfectly straight and vertical stem, but bare on the Southern and South-Eastern sides. This flagstaff-like appearance is not caused by the removal of the branches on this side, but by the destructive effect, which the wind has on the soft tissue of the buds in spring. Only the terminal shoot and those on the leeward side are allowed to develop, while the others are destroyed as soon as they show themselves.

While the effects of wind described so far are not specifically South African, as many other countries exhibit the same or similar phenomena, there is one feature of the wind that prevails over a large part of South Africa during the summer months, which has no where else such a preponderating influence on the vegetation. That is the cloud covering of many of our mountains which generally accompanies the South and South-East winds and which supplies a considerable amount of moisture to the vegetation of the mountains during_the season, which is otherwise dry. It is this property of the South-East wind which must be looked upon as one of the chief agents in the delimitation of the area or areas of that famous vegetation of the

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PINE ON THE SLOPES OF THE DEVIL'S PEAK. [Photo by E. Dyke.

South-Western districts, known to the botanical geographer as the Cape-Flora.

In the extreme South and South-West, where the winter rains are constant and regular, the valleys and plains are covered with proteas, heaths and Restionaceae, but North of the Langebergen these plants do not occur in the lower regions, being confined entirely to the mountains. The reason is a twofold one, for this remarkable distribution of the plants is partly due to the nature of the rocks; the mountains consisting of sandstone and the plains and hills mostly of shales; but principally it is caused by the clouds which supply moisture to the plants of the mountains, but not to the valleys or the hills.

On the Zwartebergen, the Anysberg, Touwsberg, the Kamanassi mountains, the Wittebergen near Matjesfontein, and a number of others, the line of demarcation between the karroid vegetation of the hills and the Cape-Flora is always well defined, for there is no mixing of the two formations. But even on the Cape Peninsula the contrast between the region of the clouds and the lower slopes is most remarkable. Many of the most famous flowers of the Cape are confined to the mountains, where the summer climate is so largely modified by the moisture-bearing clouds. The Disa uniflora, more justly called D. grandiflora, for specimens with 2 or 3 blooms are not uncommon, the blue Disa graminifolia, also known as Herschelia coelestis, the beautiful Disa longicornu and D. ferruginea, and many other orchids, do not descend below the region of the clouds. The gorgeous Nerine sarniensis, the Anemone capensis, Watsonia Meriana, and many beautiful heaths are confined to the heights, and the Cape cedar of the cedar mountains thrives at its best only above the 3000 feet level, where the winter brings more rain and the summer the clouds. There are hundreds, probably thousands, of species of plants which are dependent on this source of supply, and cannot exist where it fails, but it would be impossible to deal with them here

How considerable the quantity of water is, which the South-East clouds bring, and which, it must be remembered, is not indicated by our rain gauges, was well demonstrated during a five-days' SouthEast storm in February, 1905, when the top of Table Mountain was transformed into a swamp, as if it were midwinter, although not a quarter of an inch of rain had fallen during a period of three weeks.

The area over which the South-East clouds extend is very considerable, for it reaches from Cape Point to the Bokkeveld and the Kamiesbergen in the North, and to the mountains of Uitenhage in the East, occasionally even to others further East and North. But the plants referred to above as some of the chief elements of the CapeFlora, cannot thrive where the winter is dry, hence, being dependent on the rain of the winter months, and an intermittent supply of moisture in summer, they are hemmed in from East and North, and form a floral region of their own in a territory so small that it has no parallel in other parts of the world.

By T. LANE Carter.

[ABSTRACT.]

The first African slaves were taken to the New World by the Spaniards to work the gold and silver mines, as the Red Men had proved utter failures as labourers. Eventually the British excelled the Spaniards as slave dealers. The important part played by Great Britain in the introduction and spread of slavery in America was forgotten during the 19th Century, when the children of the men who had done so much to introduce negro slavery vehemently denounced the South for this institution. The British Parliament watched with zealous care the interests of the slave trade; slaves were forced on the Colonists for years after they cried out against the institution.

It should be remembered that the Civil War was not fought to liberate the slaves. No man in America dreamed of final emancipation, when hostilities commenced in 1860. Lincoln's Inaugural Address contains the declaration that "he had no purpose, directly or indirectly, to interfere with the institution of slavery in the States where it exists." At first Lincoln leaned to gradual emancipation, and as the war dragged on, he conceived the idea of doing away with the institution of slavery, which had brought such misery on the country. On January 1st, 1863, he signed the final Edict of Freedom. When the war came to an end there were four millions of freedmen in the South. The ex-slaves were entirely ignorant, untrained as a rule, save for servile occupations. Childlike in mind and habits, they interpreted their new liberty to mean release from restraint. 1865 they began to wander away from the plantations, to enjoy the delights of idleness, to indulge thievish and immoral propensities to the full, and to work no more and no longer than they found agreeable. The dominant party at the North, the Republican, never rested until the whites of the South, the ex-Confederates, were disfranchised, and the negroes were enfranchised.

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After the Civil War the victors did everything in their power to lift up the ex-slaves, and to debase and humiliate their race living in the South. Wholesale confiscation of Southerners' property was carried out in every State, and the lower class of politicians from the North (the "carpet baggers") promised the negroes forty acres and a mule" for their votes. Red and blue pegs were sold to the negroes with which to mark off their forty acres. A pretended deed for land, sold to ignorant negroes, commenced as follows:

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"Know all men by these presents, that a nought is a nought and a figure is a figure, all for the white man and none for the nigger. And whereas Moses lifted up the serpent in the wilderness, so also have I lifted this damed old nigger out of four dollars and six bits. Amen! Selah!"

In spite of desperate efforts to make the negro a permanent part of the political life of the country, the results attained by negro

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