Archive
TOUGHEST PLANT?
18/07/2024
I have been fascinated by bryophytes, that is mosses and liverworts, for many years. Indeed they were a major element of my doctorate research on heathland where, on pure sand, mosses grew where very little else could and helped to stabilise the ground so that other plants were able to colonise. Mosses have an extraordinary ability to grow on substrata that are hostile to many other plants – on tree bark, stones & rocks, in the deepest shade, on roofs of all kinds in the blazing sun as well as the cold extremes of high mountains and boreal habitats.
There is one moss species, though, which seems to excel at growing in the harshest habitats where even most other mosses cannot survive. This is the steppe screw-moss, a member of the family of pottiales, Syntrichia caninervis (Mitt.) Broth.[1]
[1] https://doi.org/10.1016/j.xinn.2024.100657
The steppe screw-moss is an organism of extreme environments – an extremophile. It has a wide distribution on Earth, favouring deserts from Tibet to Antarctica, indeed in arid habitats all over the world including Europe, and North America. It has hair-like structures which can collect moisture from fog and dew when there is no rain or snow. The photo of it on the left is by Sheri Hagwood of the US Bureau of Land Management (from Wikipedia public domain).
Here is an enlargement:
Scientists have been busy researching this bryophyte and its extreme temperature tolerance, dipping it in liquid nitrogen for a month and at rather higher temperatures (of -80oC) for years! That it recovers after such experimental insults is extraordinary enough, but it can also withstand gamma radiation – it can survive 500Gy (Gray units) which is a lot when you think that is ten times what would be lethal to humans.
This has led to thoughts that a species of plant with such remarkable abilities to survive hostile surroundings might even subsist extra-terrestrially. Enter the researchers again who have subjected S. caninervis to a simulated environment of the conditions on Mars (temperatures varying between -60 and 20oC, high ultraviolet radiation and low atmospheric pressure in an atmosphere of 95% carbon dioxide. Extraordinarily, all the dried moss samples placed in these conditions had a full rate of regeneration after a week of these conditions.
Happily, Betts Ecology don’t have such extreme conditions on our sites, but we do have many places where mosses grow in situations where other larger plants except perhaps lichens, cannot, such as on the tops of walls, on roofs and exposed stony paths. Throughout our sites, though, we encourage bryophytes in all habitats, even lawns – personally, I have a hatred of treating lawns with moss killers!
