Identification notes
This is a small and rather anonymous-looking plant and, unless you’re already down on your hands and knees, an easy one to miss. It’s a similar size to the very common Pohlia melanodon, but will not be found on the moist neutral to calcareous clay soils preferred by that species. Instead, look on more acid clays, often in the open.
The plants themselves are tinged slightly yellow, which is a useful pointer for this plant. The clincher, however, is its very striking (and also pale yellow) knobbly rhizoidal tubers, which you’ll usually need a compound microscope to see. These are sometimes abundant, but other times a lot of time can be spent searching for them.
To get rid of the dirt that often cakes the rhizoids of this species and often obscures its tubers, treat the plants like a tuberous Bryum and give them a vigorous shake for a minute or so in water in a small capped container. Then examine the rhizoids again microscopically and any rhizoidal tubers will then be much easier to see.
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