Deserts and semi-deserts are vast open spaces, with sandy, pebbly, or clay soils. The main distinguishing features of these corners of the Earth are the extremely low average annual precipitation (rain) and high temperatures. Moreover, the temperature can change very drastically during the day. In deserts, intolerable heat (above +50°C) can prevail during the day, and freezing (temperature drops below 0°C) can occur at night. There can also be significant temperature differences throughout the year. In semi-deserts, the temperature changes are not so stark, and the level of precipitation is higher.

Extreme conditions significantly affect the local flora and fauna. Vegetation in semi-deserts is usually sparse, and in deserts, it may be almost completely absent. Plants that reproduce by spores, such as ferns, are not capable of surviving in such a harsh climate. However, seed ferns (Pteridospermatophyta), like the shrub Ruflorinia sierra, could exist here. Also, gymnosperms could live...