In the operation of ploughing the furrow slice is separated from the soil below, and although in humid soils this layer may be left to settle by degrees, in semi-arid regions this loosened layer becomes.
The prairies of the more humid regions are covered with valuable grasses, and with masses of showy native flowers, which bloom from spring to autumn.
The Lower Austral zone occupies the greater part of the Southern states, and is divided near the 98th meridian into an eastern humid or Austroriparian area and a western arid or Lower Sonoran area.
The winters are long and marked by exceedingly low temperatures, but as they are the driest season of the year, the extremes are not so disagreeable as they would be in a more humid region.
Of the Pecos Valley, and in the Staked Plain and Edwards Plateau; and the widely extending Lower Austral zone, covering most of the state and subdivided into the Lower Sonoran or arid western part, the Austroriparian, or humid eastern, and the narrow Gulf Strip, which is semi-tropical.
The arboreous forms which least require the humid and equable heat of the more truly tropical and equatorial climates, and are best able to resist the high temperatures and excessive drought of the northern Indian hot months from April to June, are certain Leguminosae, Bauhinia, Acacia, Butea and Dalbergia, Bombax, Shorea, Nauclea, Lagerstroemia, and Bignonia, a few bamboos and palms, with others which extend far beyond the tropic, and give a tropical aspect to the forest to the extreme northern border of the Indian plain.
The spring air was heavy and humid already in Atlanta; it felt like summer.
Limit of numerous austral species, is divided into an eastern humid or Alleghanian area, a western arid area, and a Pacific coast humid area.
Subsequently, as the climate of the plains assumed a colder and more humid character, they retired before the invading forests to the high mountains.
The perennially humid regions of the Malayan peninsula and western portion of the archipelago are everywhere covered with dense forest, rendered difficult to traverse by the thorny cane, a palm of the genus Calamus, which has its greatest development in this part of Asia.