However, a significant degree of commonality exists among the plant families that dominate different desert vegetations. Thomas Schochĭesert floras and faunas initially evolved from ancestors in moister habitats, an evolution that occurred independently on each continent. This desert also harbours several other plants and animals peculiarly adapted to the arid environment, suggesting that it might have a longer continuous history of arid conditions than most other deserts. These leaves grow perpetually from their bases and erode progressively at their ends. Welwitschia has only two leaves, which are leathery, straplike organs that emanate from the middle of a massive, mainly subterranean woody stem.
One example is the bizarre conifer relative tumboa, or welwitschia, in the Namib Desert of southwestern Africa. Only a few primitive plants, which may have been part of the ancient desert vegetation, occur in present-day deserts. However, this would have been primarily before the evolution of angiosperms (flowering plants, the group to which most present-day plants, including those of deserts, belong). Get a Britannica Premium subscription and gain access to exclusive content.ĭeserts also probably existed much earlier, during former periods of global arid climate in the lee of mountain ranges that sheltered them from rain or in the centre of extensive continental regions. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.
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