Identification notes
A strikingly pretty and usually strongly coloured moss which is usually easy to recognise.
Occasionally Didymodon fallax can have semi-squarrose leaves and be richly coloured too and then further checking will be needed. Examination of stem sections will show a narrow central strand (cluster of small, differentiated cells) in D. ferrugineus (it’s wider in D. fallax). The leaf base of D. ferrugineus is also distinctly decurrent, less so in D. fallax.
If a leaf of D. ferrugineus is sectioned (aim for the lower part) you’ll see the costa it has 2-3 (occasionally 4) guide cells but no band of stereids on the ventral i.e. upper side. In contrast, D. fallax has 4-8 guide cells and 1-3 layers of ventral stereids.
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