Saturday, December 22, 2007

Intermediate screw moss Syntrichia (syn. Tortula) intermedia

I am an amateur naturalist trying to learn something about everything living in my garden.

Photo 1 (click to enlarge) shows a patch of moss growing on top of a large stone in my garden, closeby my kitchen door (at (0.9,1.5) - see here).

In fact there are a number of mosses present in photo 1. Though I've not taken the time to examine it in detail, from its appearance I believe the flat feathery one below the coin in the centre of photo 1 to be our old friend Silky Wall Feather moss (Bracythecium rutablum).

The moss that's the focus of today's posting however is that directly left of the coin with leaves arranged in little 'rosettes'.

Photo 2 shows a close up (100x magnification, 1 small graticule division = 10um) of one of the leaves. Things to notice include the tiny spines on the translucent hair emerging from the end of the leaf; the rounded leaf end; the fact that towards the mid-point along its length, the leaf narrows a little and simultaneously 'recurves' (folds over at the edge). Another microscopic feature, most easily seen in the 400x image of photo 3, are the circular cells in the mid leaf, becoming oblong at the edges. Finally, a feature of my moss shown in photo 4 (I've 'tweaked' the colour and contrast on this photo to show things up a little better) are its brown, cylindrical setae (spore capsules). Taken all together, and referring to my battered copy of British Mosses and Liverworts (E.V.Watson, Cambridge Univ. Press 1955), everything points to my moss being Tortula intermedia (Intermediate Wall Screw moss). The site of the British Bryological society has a lovely close-up photo under the alternative name Syntrichia intermedia.

Ubiquitous and persisting through the winter, mosses are inherently 'good value' for the amateur nature lover (a remark I've made previously and heard reiterated on a radio documentary I enjoyed listening to recently via the BBC website). My blog has been my introduction to the mosses and I've thoroughly enjoyed discovering that life forms I'd previously regarded as 'undifferentiated lumps of green stuff' possess, in fact, a minute individuality and beauty all of their own. This is my second Tortula moss but once you've accustomed yourself to notice the difference there's no mistaking the green rosettes of our moss above from the the frosty-white pincushions of Tortula muralis I photographed a year ago. Hooray for the beautiful bryophytes!

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