A common moss which loves to pretend to be something more interesting! This is one of those species which everyone checks again and again, believing it to be something different.
C. purpureus is a calcifuge and can be found in all kinds of places where the substrate is neutral to acidic, including acid grassland, heath, decaying fenceposts and tarmac. It is very pollution tolerant so can often be found in urban situations.
Unless it has mature capsules (in spring), it can easily be confused with a number of other small acrocarps with similarly-shaped leaves and no hairpoint. Look for a couple of key features in the field to separate it from the likes of Didymodon and Bryoerythrophyllum. Its leaf cells lack papillae and reflect light, so when you view it with a hand-lens (especially an illuminated one) its leaves look shiny, not matt. Plants also usually – but not always – have hints of red, often in stems and leaves. Unfortunately, the oft-quoted character of ‘a few teeth at the leaf apex’ is not easy to see in the field.
Under the microscope, angular and smooth leaf cells and a very stout nerve will confirm this plant.Read the Field Guide account