How did plants migrate between desert regions on different continents?

While desert floras generally evolved independently on each continent from ancestors in moister habitats, plants have migrated between desert regions through several mechanisms.1

Mechanisms of Migration

• Chance Seed Dispersal: Migration between desert regions often occurs through seed dispersal, which can be facilitated by wind, water, or animals.12
• Climate Fluctuations: During periods of drier climate over the past two million years, migration became easier between northern and southern desert regions in Africa and the Americas, leading to current floristic similarities.1
• Coastal Corridors: Plants adapted to saline soils utilize coastal habitats as migration corridors. Because these plants can thrive in both desert and coastal environments, they can spread along shorelines.1
• Ocean Currents: For some salt-tolerant species, such as the saltbush, the drifting of buoyant seeds via ocean currents provides a transport mechanism between continents, allowing them to colonize coastal areas before spreading inland.1

A notable example is the creosote bush, which is believed to have migrated from South America to North American deserts approximately 11,700 years ago.1