INTRODUCTION.

THE BOTANICAL SURVEY OF SOUTH AFRICA.

THE establishment of the Botanical Survey is one of the direct scientific results of the Union of South Africa.

Soon after Union was brought about, all the botanical work that had hitherto been undertaken by the Governments of the four Provinces, viz., the Cape of Good Hope, Natal, the Orange Free State, and the Transvaal, was placed under the care of the Union botanist, who held the post of "Chiet, Division of Botany and Plant Pathology," in the Department of Agriculture.

This concentration of work under one official head at once made co-ordination of botanical research throughout the Union possible, and brought the carrying out of a botanical survey, for which official and private workers alike had long felt the need, within the pale of practical politics.

After such a survey had been advocated and urged upon the authorities by the Union botanist, its claims were again put forward by the Scientific and Technical Committee appointed to advise the Government on various matters during the Great War.

The objects of the Survey were also at this time brought directly to the notice of the late General Botha, then Prime Minister, with the result that in July, 1918, the Hon. H. C. van Heerden, Minister of Agriculture, approved of the appointment of an Advisory Committee for the Botanical Survey, and appointed the Chief of the Division of Botany and Plant Pathology, Director of the Survey.

This Committee included the most experienced botanists in the different Provinces, who, though they were not in Government employ, had come forward and had offered their services gratuitously towards any workable scheme which might be projected for the furtherance of a botanical survey of the country.

The Advisory Committee consisted of the following botanists, whose positions were purely honorary:

Dr. I. B. Pole Evans, Director.

Mrs. Bolus, Curator of the Bolus Herbarium, Capetown.

Dr. Marloth, of Capetown.

Professor Schönland, of Grahamstown.

Professor Bews, of Pietermaritzburg, Natal.

Professor Potts, of Bloemfontein, Orange Free State.

Sir Arnold Theiler and Mr. C. E. Legat, the Director of Veterinary Research and Chief Conservator of Forests, respectively, were also placed on the Committee.

At the first Committee meeting, held in Pretoria, the broad outlines of organization were discussed, and the botanists who formed the Advisory Committee agreed to take charge of the administrative work in their

respective areas in connection with the Survey, pending the appointment of whole-time officers. For this purpose the Union was eventually divided into six administrative areas :

(1) The Cape Peninsula area under Mrs. Bolus.

(2) The Western and South-Western area under Dr. Marloth. The eastern boundary of this area stretches from George to Oudtshoorn, thence through Meirings Poort to Beaufort West, Victoria West, and Preiska.

(3) The South-Eastern

area under Professor Schönland. The eastern boundary of this area stretches from Port St. Johns to Maclear, while the northern boundary runs from Maclear along the mountain range to Naauwpoort and Victoria West. (4) The Eastern area under Professor Bews. It includes Pondoland, Griqualand East, Natal, and Zululand. The southern boundary stretches from Port St. Johns to Maclear, while the escarpment of the Drakensberg forms the western boundary line.

(5) The Central area under Professor Potts. This includes the Orange Free State and Basutoland.

(6) The remaining area, including the Transvaal. Swaziland, Griqualand West, and British Bechuanaland. falls directly under the Director of the Survey.

Under this arrangement provision was made for the carrying out of the Survey by voluntary workers, as well as by Government officers. The botanists in charge of the administrative areas were empowered to grant facilities to voluntary workers for travelling and collecting, etc., and were at the same time held responsible for all voluntary workers in their areas, so that co-ordination be obtained and overlapping prevented.

Arrangements were also made for the establishment of regional herbaria in the different administrative areas under the botanist in charge. All the necessary types and records are preserved at Pretoria in the National Herbarium, under the direct supervision of the Director of the Survey.

The chief aims of the survey are:

(1) To extend our knowledge of the South African vegetation,
so that further light may be thrown on its origin and on the
past climate of the sub-continent.

(2) To study the vegetation in its relation to agricultural and pastoral
development with special reference to veld-burning, over-
stocking, cultivation, manuring, drainage, and irrigation.
(3) To study the vegetation in particular in its relation to the unsolved
stock diseases of South Africa, and thereby extend our knowledge
of the poisonous and medicinal plants of the country.
(4) To compare and correlate the vegetation and its associated
animal and plant diseases with those existing in other parts of
the world under somewhat similar telluric and climatic conditions.
(5) To study and map the South African vegetation-units and
investigate the conditions which influence them.

(7) To publish local floras, memoirs, and handbooks dealing with
the vegetation from a scientific, economic, industrial, and
agricultural standpoint.

I. B. POLE EVANS, Director,

Africa.

CHAPTER I.

PHYSICAL FEATURES OF SOUTH AFRICA.
By A. W. ROGERS, D.Sc., F.R.S.

SOUTH AFRICA is a high-lying country with straight or smoothly curved coasts; over 40 per cent. of the area lies 4000 ft. or more above the sea, though the highest point in it is only some 10,600 ft. The region, as a whole, is therefore an elevated plateau, and that its elevation is comparatively recent geologically is indicated by the high grade of the rivers which drain it. The elevation of the country was not accompanied by any considerable increase in area at the expense of the sea floor; only in Zululand and narrow strips along the coasts is there evidence of post-cretaceous addition to the continental surface. It is probable that the country as far south as the Cape ranges has formed part of a continent ever since Palaeozoic times, and that the area north of latitude 30° has not been under the sea since the remote period when animals and plants possessing structures preservable in sediments began to live. The earliest known marine fossils in this country are those in the Bokkeveld (Devonian) beds, which stretch as far north as latitude 32°, and which formerly extended farther north to an unknown limit. The marine transgression of which the Bokkeveld fauna is the evidence was of short duration, and the only other evidence of marine conditions within the continental area behind the low-lying and narrow coast belt is given by the two fossils Conularia (doubtfully classed with the gastropods) and Eurydesma (a lamellibranch) found in the Upper Dwyka shales of the South-West Protectorate: beds of the same age in the southern Karroo have been claimed as marine, but as yet there is no clear evidence for it. With this possible exception, the Karroo formation, which is the most extensive group of sediments in the country and is in all over 20,000 ft. thick (though not at any one place), is the sand and mud derived from an area much greater than that of the present South Africa and laid down by rivers in a region comparable with the IndoGangetic plain, in so far as both were sinking areas not covered by the sea, but continuously supplied with detritus by streams and wind. The Karroo beds were formed on the hypothetical continent of Gondwanaland (Suess), and their closest analogues are in Brazil, the Argentine, and the Falkland Islands, while perhaps rather less closely related successions of rocks are in the southern continent (King Edward and Victoria Lands), India south of the great ranges, and Australia. The important point about these Gondwanaland rocks for our present purpose is that they were deposited in fresh water or on land, and contain relics of animals and plants which lived on land during the long period from the carboniferous to the jurassic. Our knowledge of these rocks and their fossils is at an elementary stage, but the results won hitherto promise information of the greatest importance for the student of the evolution and distribution of living things.