Rivers, springs and flushes
The rocks, gravels and trees in and beside running water are another productive habitat. We have already mentioned the important species that occur on rocks in ravines in our western woodlands but many other interesting species occur in this riparian (riverside) habitat.
Starting up in the hills, the cold water of springs and flushes has its own distinctive flora and the bright greens and reds of the tiny rills are an attractive feature of most coires. One of the most common species is Fountain apple-moss Philonotis Fontana, often growing with Starry saxifrage, and producing large and distinctive apple-green capsules. There are liverworts here too, one of the most widespread being Cordate flapwort Jungermannia exertifolia ssp. cordifolia which forms dark-green, swelling cushions in springs. Most of the rarer species, such as Broad-nerved hump-moss Meesia uliginosa (see back cover) occur where there is some lime in the run-off so, again, the band of calcareous mountains in the central Highlands, of which Ben Lawers is the best known, includes the most important sites.
Lower down in the burns and small rivers, any stable rock or gravel will have its covering of bryophytes. In the Highlands, the most common species here are Yellow fringe-moss Racomitrium aciculare, Rusty feather-moss Brachythecium plumosum and Water earwort Scapania undulata, and where the water is acidic these species can be overwhelmingly abundant. On slabby rocks at the side of these burns the beautiful Flagellate feather-moss Hyocomium armoricum can form large carpets. In both faster flowing burns and more placid water the long fronds of Greater water-moss Fontinalis antipyretica are a familiar sight, often one of the first mosses with which people become acquainted.
Even in the lower, meandering stretches of the rivers on the easier gradients in the east of Scotland, where rock surfaces are uncommon, the silt that accumulates on tree trunks in the flood zone provides a home for a few typical species. Probably the most common are Many-fruited leskea Leskea polcarpa, River bristle-moss Orthotrichum rivulare and Water screw-moss Syntrichia latifolia and there are also a few sites for the scarce species Spruce’s bristle-moss Orthotrichum sprucei. In areas of carr on the Insh Marshes by the River Spey, some of these plants can occur in silt on trees a metre or more above head height, a reminder of winter water levels.