Identification notes
Unlike many species of Bryum, B. alpinum is usually easy to recognise, at least when it is growing out in the open in hill country. Then it is commonly richly coloured with a strongly metallic lustre and would be hard to mistake for much else. In ideal habitats, such as wet, sloping bedrock planes in or near upland watercourses, it may form dense, deep red mounds that catch the eye from a long way off. In drier places, such as gravel-surfaced tracks in high rainfall areas, it is typically much smaller and often intermixed with Scapania irrigua, Campylopus subulatus and other species.
Greener forms may occasionally be taken for Bryum pseudotriquetrum, which sometimes grows in similar places, but that species has more spreading leaves and obviously decurrent leaf bases (not present in B. alpinum). B. alpinum also lacks the strong leaf border of that species. Some bryologists claim to be able to see the mid-leaf cells of B. alpinum with a hand-lens, but they are much easier to see under a microscope. Most of our other Bryum species have shorter/wider leaf cells but only those of B. alpinum are long and narrow and incrassate.
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