In the southern part of the steppe region the plant covering is not so luxurious as in the north, and the grasses and herbs grow in isolated little bushes, between which the bare ground of the steppe remains visible. The saline earth appears much oftener, with its gray-green vegetation of salt plants, and we often find sand areas, which begin to suggest the desert steppes of the Caspian steppe country.
A characteristic plant formation in the entire steppe region is comprised by the bushes (bairaki, chahart), which generally consist of heavily tangled thickets of wild cherry (prunus chamacerosus, viskennik), spiral (tavolha), snowball (calina), almond shrub {amygdalus nana, bobovnik),
etc. They generally grow in the steppe balkas, or near them, and cover extended areas.
The Ukrainian steppe, despite contrary current opinion, does not lack tree growth. In the region of the real steppe, to be sure, we meet only forest terraces, which extend along the river courses, but in the transition zone we still find woods and groves, which not only appear in river valleys, but also cover the plateaus between these. The oak, the white beech, the maple, the poplar, the wild apple and pear trees, are the chief representatives of the tree species of the woods of this section. Even the pine ventures as far as the district of Kharkiv.
Besides the forest terraces, the rivers of the steppe region are accompanied by the formation of the so-called plavni. They are thickets of sedge and reeds, with luxuriant willow and alder growth; in drier places, which are flooded only during high-water time, real oak forests are added. With pleasure the eye of the traveler, wearied by the uniformity of the steppe, rests upon them.
As to the origin of the steppes of the Ukraine, scholars differ. Every one of them thinks he has found the only correct explanation. In reality, the origin and preservation of the Ukrainian steppes can be traced to the combined action of various causes. In the first place there is the continental dry climate. The amount of rainfall is too slight for the development of forest-flora; the drought of the summer and fall too long.
A minor cause is the salt content of the steppe-soil, which, however, is apparent only in places. On the other hand, the shape of the ground is very important. Where the land is level, where the dry steppe winds have free play and the rainwater cannot easily dissolve and wash away the salt of the soil, the steppe prevails. Where the land is cut by river valleys and balkas, however, there is more shelter from wind, more moisture, and no salt in the soil,
so that conditions are given which are favorable for the development of tree vegetation. For this reason not only the valleys of the rivers, but also the balkas, which but seldom carry water, have always had tree growth, and even woods and groves. The trees which are planted there thrive very well, while attempts at cultivation in the real level steppe almost regularly fail. The most important foundation for the existence of steppes, however, is their character as remains of the old post-glacial steppe formation. Since the beginnings of the alluvial epoch, its territory is being won by the forest, which is constantly pushing forward toward the south and southeast, using the river valleys as the main lines of advance. In this advance toward the south, the forest has now been stopped by man before it was able to reach the shore of the Black Sea and the Sea of Azof.