Monday, February 20, 2012

Resurrection



This is one of the many cushions of Tortula moss that grow on the felt-covered roof of our garage, which is beginning to resemble an ocean studded with miniature rainforest-covered islands.


At this time of year the moss plants are lush and are growing well on mild, wet winter days, but in summer they can be baked by the sun during periods of drought that can last for weeks (if we're lucky!). This moss genus has a remarkable mechanism for resisting the long term effects of drought, thanks to specialised proteins called dehydrins and rehydrins within the leaf cells that protect the delicate cell membranes when the plants dry out and when they rehydrate again after rain.


This is a very droughted sample of a closely related species called Syntrichia ruralis subsp. ruraliformis (which used to be called Tortula ruraliformis before taxonomists changed their minds about its name). It grows in environments that are even more arid in summer than our garage roof - on coastal sand dunes. I subjected it to artificial drought - 10 days on a sunny indoor window ledge with no water..... 


...... and here it is five minutes after one half  of the cushion has been re-wetted, simulating rainfall ....


... and five minutes later still after the whole cushion has been re-wetted...... flourishing green moss again (Syntrichia ruraliformis leaves are naturally yellowish-green).


There are several plants commonly referred to as 'resurrection plants' (see Google for more) that have evolved the capability for this apparently miraculous recovery after drought and, understandably, the underlying physiological and biochemical mechanisms that allow them to tolerate drought are of great interest in scientists who are working towards breeding more drought-tolerant crops.


Some mosses  are much tougher than they look. They were, after all, amongst the first plants to colonise the land surface around half a billion years ago..... and they are still here, after five major mass extinction events and drastic climate changes. Maximum respect for Syntrichia and related Tortula species, for sheer resilience and durability.

12 comments:

  1. That is a remarkable recovery in a very short time. It looks totally dead beforehand. Amazing nature.

    I notice that one of your tags is sand dunes and was reminded that my niece wrote a thesis on the movement of them and (I think) got her Master's degree for it.

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  2. Respect indeed! Very interesting, thanks.

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  3. They kind of put 'mans' survival efforts to shame really.
    Tough plants.

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  4. That is fascinating. When I've seen apparently dead mosses on dry stone walls I've appreciated they were likely to come to life again but I never for one moment imagined it was so instant. I must have a play next time I'm out walking and have a water bottle with me. Another great post, thank you, Phil.

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  5. That's extraordinary Phil. Looking at your photos I am filled with the same sense of wonder that I get when I see a Wych Elm 'Phoenix Tree' (Ulmus glabra) sprouting away from the base of a tree destroyed by Dutch Elm Disease. It never fails to amaze and humble me.

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  6. Fascinating experiment! Moss is such an oft-overlooked class of organisms in our natural world, but as demonstrated here, is amazing stuff.

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  7. Hi toffeeapple, I've long been interested in the flora and fauna of sand dunes - there are some fine examples on the Northumberland coast that sometimes have wonderful displays of orchids

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  8. Hi Jennifer, I'm hoping to get down to Newby Hall in spring to have a look at your beautiful stone sculptures. Really enjoy your blog ...

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  9. Hi Keith, if evolutionary success was measured in long-term persistence, then mosses would be in the Champions' League!

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  10. Hi John, I think they do get some water during dry spells in summer via dew at night, which condenses on those hair points on the leaves - which many mosses that survive in similarly sun-baked habitats seem to possess.

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  11. Hi Dougie, amazing how tenacious life can be, isn't it...?

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  12. Couldn't agree more swanscot - and exquisitely beautiful when you magnify them a bit...

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