Quick facts

Common name(s): swan’s-neck thyme-moss, forest star moss

Scientific name: Mnium hornum

Family: Mniaceae

Origin: native

Fruiting season: frequent

Habitat: woodland

What does swan’s-neck thyme-moss look like?

Mosses are simple, rootless evergreen plants that don’t have flowers or seeds but reproduce by spores. Swan’s-neck thyme-moss is one of Britain’s most common mosses. It is a dark, dull green, with large 'leaves' that are almost fern like and velvety. In spring the new, almost yellow leaves contrast with the older, dark-green leaves.

Leaves: around 4mm long, but can be up to 8mm towards the tip of the shoot. Erect and spreading when wet, and contorted when dry. They have a toothed border of long, narrow cells. Leaves grow parallel to each other and taper off to a point at the end.

Stems: dark reddish-brown and yellowish-green above, upright, 2–4cm tall, densely hairy.

Sporophyte/spores: spore capsules (sporophytes) are produced by female plants. They are 5mm long with the lid narrowing abruptly into a very short point. The stalks (seta) supporting the capsules are 2.5–5cm long.

Not to be confused with: other mosses in the Mnium genus.

Where to find swan’s-neck thyme-moss

In the UK it is often found in damp woodland conditions, particularly when the soil is acidic. Typically, this is in oak-birch woodlands, but also beech or pine woods. It is abundant on the ground, but also grows on logs, rocks, tree bases and along stream banks.

Swan’s-neck thyme-moss is native to Europe and eastern North America.

Did you know?

Mosses originated from aquatic plants and still have a number of features in common with them. Their pores, through which they absorb water, are always open and they require constant moisture.

Credit: John Bridges / WTML

Value to wildlife

Moss offers habitats for other plants, tiny invertebrates, frogs and fungi. Some larvae of micro-moths and lace bugs feed only on moss. Other insects hunt among moss for prey. The insects from moss also feed bats and birds. Squirrels use moss to line their dreys and dormice hibernate in nests made under moss.

Uses of swan’s-neck thyme-moss

Traditionally, swan’s neck thyme-moss was used to stuff mattresses because people believed it would help them sleep better.
Early tests carried out by scientists have discovered that the moss contains seven fatty acids, including arachidonic acid which helps to raise immunity and inflammatory responses.

Threats and conservation

Swan’s-neck thyme-moss is common and not currently under threat at the UK scale.


Types of moss in the UK: what they are and where to find them

Kate Lewthwaite  •  30 Jul 2018

Moss is marvellous! Find out why and see some common species to spot.