Desert perennials can withstand considerable dehydration; some of these plants being quite able to tolerate desiccation to about 50% of their dry weight (in mesophyte this value averages about 200%)—that is they can tolerate protoplasmic desiccation to a much larger extent compared to ordinary mesophytic plants. The gelatinous coating on the cell walls of the blue-green algae perhaps plays an important role here.