Mnium hornum, also known by the common names horn calcareous moss or swan's-neck thyme-moss, is a species of moss in the genus Mnium.[1]
The upright stems of swan's-neck thyme-moss are 2 to 4 cm tall. Leaves are 4mm to 8mm long, with a toothed border of long, narrow cells. The vein ends a slightly below the tip of the leaf. The lower part of the stem has small, narrow triangular leaves. Capsules are 5mm long, with a lid that narrows abruptly into a short point. The seta is between 2.5 and 5 cm long.[2]
Swan's-neck thyme-moss is native to Europe and eastern North America.It is commonly found in damp woodland conditions, especially in acidic soil, such as oak-birch, beech and pine woodlands. It is found on the ground, logs, rocks, tree bases and along streams.[3]
In 2012, researchers in Serbia found that Mnium hornum could be used as a potential source of arachidonic acid.[4]