This small, anonymous-looking acrocarp lacks any conspicuous field characters, although it does have a particular colour – dark olive green, approaching black in some populations. Other good features are its very narrow and sharply-pointed leaves, which are erect. When dry, leaves often lie appressed to the stems or are at most slightly flexuose, a good character to separate from similar-looking cushion-formers. Microscopically, the leaf cells are distinctive, being very thick-walled.
Many people think of this species as a moss of tufaceous seeps, limestone pavement and other strongly calcareous substrates. However, it can also be abundant on metalliferous mine waste, for example in disused tin and copper mines in Cornwall and elsewhere.
- Hymenostylium recurvirostrum var. recurvirostrum: the nominate variety, a smaller plant with non-sheathing leaves and a narrow costa.
- Hymenostylium recurvirostrum var. insigne: rare, mainly in Scotland, a larger plant with a wide costa and sheathing leaf-bases, in ravines and on calcareous rock ledges in the mountains.