Swimming with desmids …

My sampling trip to Upper Teesdale in search of desmids (see “Hunting for desmids in Upper Teesdale”) has now yielded another picture, this time figurative rather than semi-abstract.   I have tried to depict the world inside a Sphagnum bog so have shown two desmids underneath a canopy of Sphagnum leaves.   The Sphagnum leaves have a characteristic structure, with chlorophyllose cells alongside water-filled “hyaline” cells. The desmids live, in effect, inside a glass-roofed conservatory although I have probably conveyed an overly bright impression of the subaquatic world of the bog.   The reality is that the slow decay of Sphagnum yields brown humic materials that create an altogether murkier environment.


The microscopic world of an Upper Teesdale Sphagnum bog, with desmids living in the space underneath Sphagnum leaves.   The chlorophyllose cells are about ten micrometres in diameter (1/100th of a millimetre) whilst the desmid in the foreground (Cosmarium ralfsii) is about 100 micrometres (1/10th of a millimetre) across.

I’ve tried to illustrate the structure of a Sphagnum leaf in the diagram below.   Compare this with the photograph in “More from Upper Teesdale” (showing the view from above) the leaf to get an idea of how the leaf is constructed.   It also demonstrates why Sphagnum moss is capable of absorbing so much water: two-thirds or more of the leaf is composed of empty space and there is even a convenient pore to let the water in.


A schematic cross-section through a leaf of Sphagnum showing the arrangement of hyaline and chlorophyllose cells.   The chloropyllose cells are about 10 micrometres (1/100th of a millimetre) across.

My illustration of the microscopic world of a Sphagnum bog is a step outside my comfort zone, as I tried to combine the various elements together from separate microscopic images.   Microscopy tends to flatten perspective, partly because specimens are squashed onto microscope slides but also because of the focal length of the lenses involved.   Added to this was the problem of depicting the sinuous chlorophyllose cells in an approximation of single-point perspective.   Almost as soon as I had finished the picture, I was thinking about how I could be improving the next version. Striving towards realism is, itself, an ongoing mind experiment that offers tantalising glimpses of an otherwise hidden world.