Ditrichum gracile in calcareous gravel of forestry road verge
Ditrichum gracile (Banwen) with long silky leaves
The Ditrichum here forms dense turfs in places, so I looked at it closely, particularly in view of recent postings. The occurrence of an obvious tomentum (relatively dense on some shoots) encouraged me to take some specimens back for closer inspection.
Rhizoids on lower part of D. gracile stem
However, leaf length and general morphology clearly point to gracile, as does the absence of short-leaved, deciduous branches (see Sam's post on 30/1/15). Also, when dry, the long leaves become distinctly flexuose and twist around each other at the tip. This may be a much more reliable character for gracile than the density of the tomentum, which looks like a more plastic, phenotypic character.
Dry, flexuose and twisted leaves of D. gracile
But this also lends weight to Sam's comments regarding the occurrence of intermediate forms and safety of the split between gracile and flexicaule.