Most mosses ask for shade and damp. This one makes its living in the last place you would think to look for a moss: open desert. Syntrichia caninervis grows across the cold drylands of the world, from the Mojave to the gravel plains of central Asia, binding bare ground into a living skin. It endures heat, cold, drought and radiation that would finish almost any other plant, and in 2024 it drew a run of headlines for shrugging off conditions designed to mimic the surface of Mars.
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A moss where none should grow
You will not find this one furring a shaded log. Desert moss is a plant of biological soil crusts, the thin dark skin of moss, lichen and cyanobacteria that holds together the surface of cold deserts. It grows in the Mojave and Great Basin of North America, across the Middle East, through the steppes and the Gobi of inner Asia, and on to the fringes of Antarctica, wherever the ground lies open, stony and starved of rain. In the Gurbantunggut desert of north-western China, where much of the recent research has been done, it is the dominant moss of a crust that may be the only green thing for miles. Its growth is slow past imagining; a patch you could cover with one hand may have taken decades to form.
How it drinks without rain
The knack that lets it live out there is a tolerance of total drying that few plants can match. Through a drought it does not fight to hold water so much as surrender it completely, drying to a brittle, blackened crisp and putting its life on hold until the next rain. As the leaves dry they twist and curl inward around the stem, which shields their surface from the sun. Each leaf ends in a long white hair as well, the same glassy awn that gives other dry-ground mosses their white tips, and in this species the hairs actively gather water, condensing dew and fog and funnelling it down to the shoot. When moisture finally arrives the plant rehydrates and switches its metabolism back on within seconds. The references describe shoots reviving after years stored dry in a drawer, and desiccation-tolerance of that order is the groundwork for everything else it can do.
The experiments that made the news
The Mars headlines came from a 2024 paper by a team at the Chinese Academy of Sciences, published in the journal The Innovation. They put dried desert moss through a battery of extremes and watched what regrew. It came back after a spell in liquid nitrogen at around minus 196 degrees; it tolerated gamma radiation at doses many times over what would kill a person, and in one odd result a moderate dose appeared to spur regrowth rather than hinder it. Dried plants then went into a chamber tuned to Mars-like settings, an atmosphere almost all carbon dioxide, lurching temperatures, fierce ultraviolet and very low pressure, and after up to a week inside they regenerated once rehydrated. Prior drying, every time, helped them cope. What the study does not show matters as much as what it does. Surviving a sealed chamber is a long way from growing, photosynthesising and reproducing out in the open on a planet whose surface holds no liquid water. The work tells us this moss is astonishingly tough; it does not tell us Mars is about to turn green.
What it does for the desert
Set the space travel aside and the plant counts for far more in what it does at home. Biocrust mosses are the quiet engineers of dryland soil. Their shoots, and the filaments spreading beneath them, knit loose sand and grit into a crust that stands up to wind and rain, so ground that would otherwise blow off or wash into gullies holds its place. That crust soaks up and keeps the little rain that falls, it gives seeds a foothold, and, through the cyanobacteria living alongside the moss, it pulls nitrogen from the air and feeds it into some of the poorest soil anywhere. Lose the crust to trampling, grazing or wheels and the bare ground beneath erodes fast and mends with painful slowness. A good deal of desert restoration now hinges on getting mosses like this one re-established, and researchers are learning to raise it deliberately for the task.
Leave it where it lies
I grow a fair range of mosses, this one excepted, and I would gently steer you off trying. It belongs to a habitat you could never honestly recreate on a windowsill, and, more to the point, wild biocrust is fragile and desperately slow to heal; a single careless bootprint can wipe out a lifetime of growth. If you want to understand how any moss rides out a dry spell, the general story sits in how moss survives drought, and the craft of bringing a parched cushion back to life runs through reviving dried moss. Desert moss simply pushes those tricks to an edge the rest of the moss world rarely approaches, which is why, out of thousands of candidates, it was this scrubby survivor that scientists packed off to a pretend Mars.