The vegetation is closely correlated with topographical regions. The high mountainous country of the west is grassland; the grass is short (seldom more than three feet high) and hardy; trees and bushes are rare; the mountain slopes are seldom gentle enough or fertile enough for largescale planting, and are poor cattle pasture, but quite good enough for grazing sheep. The midlands with their more gentle undulations are clothed in taller grass and have occasional clusters of trees and bush. The whole area is suited for mixed farming. Thorn-trees and bush dominate the lowveld, which is the best area for cattle and also has stretches of fertile black turf soil. Roughly half of Swaziland is estimated as capable of cultivation and afforestation, though in 1938 approximately 75% was devoted to grazing and only 10% to cultivation.(D Prior to 1894 a large tsetse-fly belt stretched from the Zambesi through Portuguese territory and the Lubombo flats southwards as far as Northern Zululand. The rinderpest of 1894 seemed to drive away the fly, at the same time as it seriously depleted the herds, and most of Swazi territory, apart from an area round Barberton, was free of fly until 1946, when it reappeared in some of the eastern areas.(2)
Throughout the country the rainy months are generally the hot months (October to March), with light rains in September and April. Rainfall varies considerably from year to year, but is more evenly distributed in the highveld than in the lowveld, where there is a constant threat of drought and rains tend to be concentrated in a few violent storms. The average annual rainfall at Mbabane in the highveld is 55.6 inches, at Bremersdorp in the middleveld 36.8 inches, and at Sipofaneni in the lowveld 26.5 inches. In the dry season most rivers dry up or are reduced to a mere trickle.