Troglodyte moss, slowing turning to stone ...

When I was mooching around in the entrance to this old ironstone mine near Port Mulgrave on the North Yorkshire coast yesterday I found this ....

..... unusual Whorled tufa-moss Eucladium verticillatum, lurking in the gloom ....

... in a zone where there was just enough light for it to grow into these dense cushions. As the common name suggests, this species is associated with places where tufa forms, where mineral-laden (usually calcareous) water, slowly percolating through it, gradually turns the moss to stone. If you double-click on his image and look at plants on the right-hand edge  you can see that some are almost completely 'petrified' in mineral pillars with the moss inside. I guess that those further from the entrance that grow more slowly tend to become engulfed first, while those nearer the light grow faster and survive.


 The usual tufa mineral deposit is calcium carbonate but these ironstone cliffs are famous for their alum deposits which is mined a couple of miles away at Boulby, so I think that in this case that's what the petrifying mineral is.

You can see the crystalline deposits here ......

..... here ....

..... and here at increasing levels of magnification. 

The densely-packed individual moss leaves are extremely long and narrow, with a distinct mid-rib and minute teeth along the leaf edge.


You can read more about plant life in cave entrances by clicking here.