Identification notes
Like its sister, S. auriculatum, this common species of mildly basic habitats is variable and frequently strikes fear into the heart of the bryologist brave enough to attempt an identification.
But, as long as you can see that it has the curled upper branches (the so-called ‘cow’s horns’) characteristic of well-grown shoots of species in Sphagnum Section Subsecundum, then you are nearly home and dry. The next step is to carefully examine a whole shoot. Are the spreading branches clearly differentiated from the hanging ones? If so, it won’t be S. auriculatum, where they look similar. Then check the lower stem colour – a dark brown or black stem rules out S. contortum, leaving only S. inundatum and the scarce S. subsecundum, both of which can be quite brightly coloured, with yellow and orange hues.
Spreading branch leaves are often asymmetrical and turned to one side, making plants look a bit prickly/spiky. This is also a useful additional character to rule out S. auriculatum, which typically has smooth branch outlines. Microscopically, S. inundatum usually has longer stem leaves than S. subsecundum.
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