Tortula acaulon

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Identification notes

This is much the commonest of the ephemeral mosses with immersed, cleistocarpous capsules i.e. they do not dehisce via a lid, but disintegrate when spores are mature. The nominate variety acaulon prefers enriched as well as disturbed ground and can usually be found in intensively managed arable land and in garden borders with the likes of Bryum rubens, Barbula unguiculata and Tortula truncata.

Of the three varieties currently recognised, only T. acaulon var. pilifera can be confidently named in the field – its very long, white hairpoints are striking. It’s usually – but not always – found near the sea, so is likely to be temperature-sensitive.

Read the Field Guide account

Species varieties

There are currently 3 varieties recognized in Britain and Ireland:

  • T. acaulon var. acaulon (was Phascum cuspidatum var. cuspidatum)
  • T. acaulon var. pilifera (was Phascum cuspidatum var. piliferum)
  • T. acaulon var. papillosa (was Phascum cuspidatum var. papillosum)

Similar Species

Although a small moss, T. acaulon is larger than other small mosses with similar capsules and it often occupies subtly different habitats. Microbryum floerkeanum, for example is far smaller, and although it is also found on disturbed, base-rich soils, they are never as enriched.