They have developed the ability to reversibly activate their metabolism, limiting photosynthesis and growth to wet periods when the cells are rehydrated. During hot, dry periods, the cells enter into a quiescent state. Although photosystems I and II (PSI, PSII) are damaged during high light and dryness, in vitro studies have shown that PS I and PSII are self-repaired and operational within minutes of the cell’s rehydration