Benmore Botanic Garden’s new moss trail

Written By Jenny Tweedie

By Dr Max Coleman

Benmore Botanic Garden

To paraphrase the introduction of The Hidden World of Mosses by Neil Bell, nearly everyone has heard of moss, most people can recognise moss, but hardly anyone knows about moss. It’s true that mosses do tend to get overlooked, mainly due to their small size and because to fully appreciate them you need a lens. This is why Benmore Botanic Garden has created a moss trail – lens provided – to highlight these wonderfully diverse and important native plants.

When we talk about moss what we are really referring to is a group of related plants that botanists call bryophytes. The group includes mosses, liverworts and hornworts. A major difference between mosses and larger plants is that nearly all mosses lack well-developed internal structures to move water around. Instead, they have thin, permeable cell walls, and water travels over and through them. The downside of this is that they quickly dry out and this is why they are both small and particularly abundant and diverse in wet places.

Prickly featherwort (Plagiochila spinulosa). Credit Des Callaghan  

Benmore Botanic Garden is an ideal place for a moss trail as it is located within the so-called temperate rainforest zone that covers much of western Britain. Here the annual rainfall is high and more evenly spread throughout the year, and the natural vegetation would have included much more woodland. This habitat is a kind of temperate rainforest, partly defined by the mosses covering branches, trunks, boulders and the ground in a luxuriant, evergreen blanket of incredible diversity. Mixed among the mosses you find colourful lichens in many forms. Ferns complete the verdant picture, some small, filmy and moss-like, adding to the sense of diversity.

Despite being individually small, mosses can be prominent features in the landscape. Along the moss trail you will encounter carpets of bog moss (Sphagnum species) and the distinctive and rather strange hummocky formations created by common haircap (Polytrichum commune).

Common haircap (Polytrichum commune). Credit Des Callaghan

The area of Argyll that surrounds Benmore Botanic Garden is home to over 800 species of bryophytes. This is a truly remarkable tally that amounts to about 4% of the global total for mosses, liverworts and hornworts combined. But perhaps this level of diversity is not so surprising when you consider that it rains on more than 240 days each year at Benmore!

The mosses create species-rich temperate rainforest, but some, notably the bog mosses, store vast amounts of carbon in the form of peat. Poorly drained ground in the rainforest zone naturally develops into blanket bog. Trees may struggle in such waterlogged conditions, but the dead remains of the mosses that thrive in this wet habitat gradually accumulate and store carbon. The dead moss does not decompose because oxygen levels are extremely low beneath the bog surface, preventing the growth of microbes that would otherwise breakdown dead plant matter.

So, next time you see a moss, stop and give it a closer look and some love. Consider how many kinds of moss there are – nearly 1,000 in Scotland – and the many important roles they play in the natural environment.

Jenny Tweedie
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