Bank Haircap Moss (photo: Steve Orridge)

Mosses, liverworts and hornworts

About mosses, liverworts and hornworts

Mosses, liverworts and hornworts are bryophytes. These are mainly green, flowerless plants that reproduce by means of spores and/or by asexual gemmae or tubers. They have no roots, no vascular system and no xylem or phloem to conduct water internally. They are the simplest of plants, and resemble the first plant species to develop on land over 400 million years ago.

Bryophytes are very important ecologically, stabilising soils, creating humus on bare rock and ‘laying the ground’ for other plants, and helping to control the cycling of water and nutrients, especially in woods and upland areas. Species such as sphagnum mosses form vast bogs and mires that can lock up massive quantities of carbon, helping to mitigate climate change. (See our reprint of the recent article ‘An epic global study of moss reveals it is far more vital to Earth’s ecosystems than we knew’ at the bottom of this page.)

There are over 25,000 secies of bryophyte worldwide. About 1,000 species are found in Britain, of which mosses comprise about 760 species, liverworts about 300 species and hornworts 4 species.

Mosses

Mosses come in 2 broad growth forms: Acrocarps and Pleurocarps. The Acrocarps grow upright and form cushions, clumps or mats. They have their spore capsules (known as setae) on the tips of their shoots. The Pleurocarps are sprawling and grow over their substrate – rock, soil or wood – or through other vegetation. They have their setae on the sides of their shoots.

Moss foliage consists of simple, undivided leaves that are about one cell thick, although some species’ leaves have midribs and/or thickening of the outer edge.

Liverworts

Liverworts come in 2 broad growth forms: thallose and leafy.  Thallose liverworts resemble miniature seaweeds with simple, ribbon-like forms. These may have no internal structure and look translucent when held up to the light, or they may have more complex forms with internal structure, looking opaque when held up to the light, and may have pores over the upper surface. The leafy liverworts have stems with rows of leaves down each side and often a third row of smaller, differently shaped leaves on he underside. The leaves may be lobed or divided, unlike mosses. The stems may grow along the ground or through other vegetation.

There is an intermediate form of liverwort in the genus Fossombronia, which resembles a miniature lettuce.

Hornworts

Hornworts were for a long time classified with liverworts but have been recognised as a distinct group. They are thallose in form and are named for their long, horn-like sporophytes. Only 4 species are recorded in Britain.

Mosses, liverworts and hornworts (Bryophytes) in the High Peak

For these buttons with the solid borders to work properly you will need to be registered and logged into iNaturalist. This is a free and extremely useful app. See our ‘How to record wildlife’ page for more information and tips on how to use it.

Takes you to the up-to-date list and photo galleries of all bryophyte observations within the High Peak area, as recorded on iNaturalist

Takes you to the up-to-date list and photo galleries of all bryophyte observations within the ‘Buxton polygon’ area, as recorded on iNaturalist and collected by the Buxton Biodiversity Recording Group project

We are building up a set of photo galleries of the mosses and liverworts that we have found in surveys of the various wildlife places in and around Buxton. Click on the buttons below to go to the currently available photo galleries.

Identifying mosses, liverworts and hornworts

Mosses and Liverworts of Britain and Ireland: a field guide.

Edited by Ian Atherton, Sam Bosanquet, Mark Lawley.

British Bryological Society

The most modern and up-to-date field guide to the mosses, liverworts and hornworts of Britain and Ireland. An excellent and comprehensive guide produced by a team of expert bryologists, with good photographs and identification keys, and all species identified under their English and scientific names.

Guide to mosses and liverworts of woodlands

Guide to mosses and liverworts of towns and gardens

Field guide to sphagnum mosses in bogs

Sphagnum mosses: field key to the mosses of Britain and Ireland

Field Studies Council

Field Studies Council

Handy and robust laminated foldout guides in the excellent FSC series of publications.

Gathering Moss: A Natural and Cultural History of Mosses

Robin Wall Kimmerer

Oregon State University Press

A beautifully written mix of science and personal reflection on how mosses live and how their lives are intertwined with the lives of countless other beings. An exploration of the stories of mosses in scientific terms and in the framework of indigenous ways of knowing. Fascinating and informative.

Information and guidance

An excellent website. The BBS welcomes anyone interested in the study and conservation of mosses and liverworts. Whether you are a beginner, keen to improve or have been studying bryophytes for many years, the society aims to support you, with a full programme of field meetings, a paper reading meeting, recording and research projects, an international academic journal, a lively membership magazine and an extremely popular Field Guide to Mosses and Liverworts.

An epic global study of moss reveals it is far more vital to Earth’s ecosystems than we knew

David John Eldridge, Professor of Dryland Ecology, UNSW Sydney

Manuel Delgado-Baquerizo, Ecosystem ecologist, Spanish National Research Council, Consejo Superior de Investigaciones Cientificas (CSIC)

Published in The Conversation, May 1st 2023. Reprinted under Creative Commons Licence.

Mosses are some of the oldest land plants. They are found all over the world, from lush tropical rainforests to the driest deserts, and even the wind-swept hills of Antarctica.

They are everywhere; growing in cracks along roads and pathways, on the trunks of trees, on rocks and buildings, and importantly, on the soil.

Yet despite this ubiquity, we have a relatively poor understanding of how important they are, particularly the types of moss that thrive on soil.

New global research on soil mosses published today in Nature Geoscience reveals they play critical roles in sustaining life on our planet. Without soil mosses, Earth’s ability to produce healthy soils, provide habitat for microbes and fight pathogens would be greatly diminished.

A global survey of soil mosses

The results of the new study indicate we have probably underestimated just how important soil mosses are.

Using data from 123 sites across all continents including Antarctica, we show that the soil beneath mosses has more nitrogen, phosphorus and magnesium, and a greater activity of soil enzymes than bare surfaces with no plants.

In fact, mosses affect all major soil functions, increasing carbon sequestration, nutrient cycling and the breakdown of organic matter. These processes are critical for sustaining life on Earth.

Our modelling revealed that soil mosses cover a huge area of the planet, about 9 million square kilometres – equivalent to the area of China. And that’s not counting mosses from boreal forests, which were not included in the study.

The strength of the effect mosses have on soil depends on their growing conditions. They have the strongest effect in natural low productivity environments, such as deserts. They are also more important on sandy and salty soils, and where rainfall is highly variable.

Not unexpectedly, mosses have the strongest effects on soils where vascular plants – those that contain specialised tissues to conduct water and minerals – are sparse.

An intimate connection

Mosses lack the plumbing that allows vascular plants to grow tall and pull water from beneath the soil. This keeps them relatively short, and means they develop an intimate connection with the uppermost soil layers.

Mosses are extremely absorbent and can attract airborne dust particles. Some of these particles are incorporated into the soil below. It is not surprising then that they have such a strong effect on soils.

Our modelling shows that, across the globe, mosses store 6.4 gigatonnes more carbon than soils without plant cover.

Losing just 15% of the global cover of soil mosses would be equivalent to global emissions of carbon dioxide from all land use changes over a year, such as clearing and overgrazing.


Not all mosses are equal

We also found some mosses are more effective at promoting healthy soils than others. Long-lived mosses tended to be associated with more carbon and greater control of soil pathogens.

The ability of mosses to provide ecosystem services and support a diverse community of microbes, fungi and invertebrates was strongest in locations with a high cover of mat- and turf-forming mosses such as Sphagnum, which are widely distributed in boreal forests.

Soils are a huge reservoir of soil pathogens, yet the soil beneath mosses had a lower proportion of plant pathogens. Mosses can help to reduce the pathogen load in soils. This ability may have originated when mosses evolved as land plants.

A special group in the desert

A special type of moss flourishes in deserts. They either live hard (perennial mosses) or die young (annual mosses).

Mosses in the family Pottiaceae are uniquely suited to life under dry and inhospitable conditions. Many have specialised structures that allow them to survive when water is scarce. These include boat-shaped leaves with long hairy tips that help to funnel water into the centre of the plant. Some mosses twist around their stem to reduce the area exposed to the sun and conserve moisture.

Desert mosses also protect the soil against erosion, influence how much water moves through the upper layers and even alter the survival chances of plant seedlings.

Other mosses have special moisture-absorbing cells (papillae) that swell up and provide them with a moisture reserve when conditions are dry.

Our global study showed that mat- and turf-forming mosses such as Sphagnum had the strongest positive effects on the diversity of microbes, fungi and invertebrates, and on critical services such as nutrient supply. Predictably, longer-lived mosses supported more soil carbon and had greater control of plant pathogens than short-lived mosses.

Protect the mosses

Overall, our work shows mosses influence important soil processes and function in the same way vascular plants do. Their effects may not be as strong, but their total cover means mosses are potentially as significant when summed across the whole globe.

But mosses are under increasing threats globally; disturbance by livestock, overharvesting, land clearing and even changing climates are the greatest threats.

We need a greater acknowledgement of the services that soil mosses provide for all life on this planet. This means greater education about their positive benefits, identifying and mitigating the main threats they face, and including them in routine monitoring programs.

Soil mosses are everywhere, but their future is far from secure. They are likely to play increasingly important roles as vascular plants decline under predicted hotter, drier and more variable global climates.