A small moss growing in the Mojave desert in California uses a remarkable protection from the desert sun – it shelters under translucent quartz stones. It is a miniature greenhouse that shields the moss from heat, cold, drought and intense ultraviolet rays.
The desert gets extremely hot in the summer and cold in the winter, and the nights can also be really cold. Botanists found the brilliant green moss Syntrichia caninervis sheltering under the quartz stones, keeping the moss cooler during hot times and warmer during the cold spells. The stones also trapped moisture under them, keeping the plants moist. The sheltered mosses grew much faster and taller than the ones left out on exposed soil without protection.
The quartz stones needed to be just right the size, around an inch thick and translucent enough to act like a greenhouse window, letting up to 4% of daylight pass through but blocking out harsh ultraviolet light that could harm the moss.
Similar miniature quartz greenhouses are used by cyanobacteria. These are entirely different organisms from plants but they can photosynthesise, and they shelter under quartz stones to survive extremely harsh climates such as the Arctic, Antarctic, Atacama and Namib deserts. It is convergent evolution – unrelated organisms evolving similar ways to cope with similar environments.
