No Water? No Problem.
Does extended drought spell ‘the end’ for all plant species?
Not necessarily.
Most vascular plants are unable to survive when allowed to desiccate to an air-dried state, that is, when they are allowed to dry to the point at which no more evaporation can occur. Seeds and pollen grains can withstand this level of dryness, but even pollen grains falter in such situations. It seems almost impossible that a full grown plant would be able to survive where a pollen grain could not, but there are in fact plants that do this.
These creatures, aptly termed “resurrection plants”, are able to survive severe water loss and regain full photosynthetic function once water is reintroduced. Resurrection plants can be placed in one of two groups based on their drought tolerance strategies. One group is considered poikilochlorophyllous, meaning that the photosynthetic pigments and photosynthetic machinery within their cells breaks down or is at least somewhat degraded during drought. Other plants are considered homoiochlorophyllous, meaning that they retain the structural integrity of their machinery but there are some slight changes in the pigments. These plants bounce back much more quickly than those whose photosynthetic machinery break down entirely.
You can find resurrection plants in the Southern hemisphere, across Africa and Australia for the most part. They tend to establish themselves in areas where large amounts of rainfall are seasonal and sporadic. Many species of resurrection plant have been identified within the herbaceous angiosperms, or the non-woody flowering plants, but none have yet been discovered among the non-flowering gymnosperms and there are no known resurrection species that are able to grow past shrub size. Some studies suggest that the ability to withstand severe drought is constrained by size since all known resurrection plants do not exceed a certain height.
Source
Bartels, Dorothea. “Desiccation tolerance studied in the resurrection plant Craterostigma plantagineum.” Integrative and Comparative Biology 45.5 (2005): 696–701.
