This very common species of base-rich rock and soil is highly variable in colour, size and even growth form. Recognising what makes it a Trichostomum rather than a Chionoloma, Barbula, Streblotrichum, Weissia or any other Pottiaceous species is important in recognising some of the less typical morphs.
First, look at the leaf margins – are they recurved, or incurved (even if only slightly at the leaf apex)? Trichostomum leaves are never recurved and those of T. crispulum characteristically look ‘hooded’ at the apex due to the incurved upper margins (there are some good images in the gallery below).
Then consider the nerve – does it end below the leaf apex or is it excurrent? Trichostomum species have a strong nerve that ends either in the leaf apex (T. crispulum), or extends beyond it (T. brachydontium). This helps to separate Trichostomum from Chionoloma, where the nerve typically ends below the leaf tip.
💡 did you know? – a very handy but little-known distinguishing feature of T. crispulum is its very dark, almost black stems.Read the Field Guide account