Fontinalis antipyretica, or willow moss, is most widely spread in the northern hemisphere. It is a true aquatic moss and can be found in many flowing and stagnant waterbodies.
F. antipyretica is a very variable moss. On the one hand, its look depends a lot on the conditions it grows in, on the other hand, there are various forms that maintain their differences even if cultivated under the same conditions. Several varieties have been described, e.g. the large-growing form F. antipyretica var. gigantea. Sometimes, F. antipyretica is hard to discern from other, far more uncommon Fontinalis species like F. hypnoides or F. howellii.
Willow moss is the most well-known aquatic moss native to Europe, and it has found its way into aquarium literature, too. However, often other aquatic mosses found in nature, like the very common Leptodictyum riparium, are confused with Fontinalis antipyretica.
To be continued...
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