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The Mystery and Magic of Moss

When my twin sister and I were young we played in the Buckinghamshire beech woods where there was an abundance of beautiful, bright green mosses. We built a mossy green theatre, roofed with what I now think was Common Haircap moss. Each stem looks like a tiny pine tree and it formed deep, soft cushions. Moss is a tactile plant. We ate our banana sandwiches on a moss bank sofa.

2024.03.Bryophyta moss by Thomas Bresson for web copyBryophyta moss. Photo: Thomas Bresson

Mosses belong to a family called Bryophytes that are often overlooked because the plants are small, grow low to the ground and are flowerless. Their beauty and complexity are revealed with a powerful hand-lens, that makes visible their exquisite jewel-like shapes.

The great American botanist, John Bartram wrote, ”I took no notice of mosses, looking upon them as a cow looks at a pair of new barn doors”, until, that is, he saw Dr Dillenius’s beautifully drawn, magnified and engraved illustrations in his History of Mosses (1741), then he was hooked. Dillenius, a German botanist, at this early date, painstakingly recorded the diversity of mosses in Britain. Bartram was, I think, underrating the observational powers of the cow!

Flowers and trees have roots and firm stems which transport water and minerals from roots to all parts of the plant. Mosses have no roots, no vascular system and are flowerless, reproducing by spores. They are related to two other groups of ancient plants: liverworts and hornworts. Instead of roots they have rhizoids, hair like structures whose function is to anchor them to rock, bark, pantiles or soil, and through which they can take in some nutrients and water.

Mosses do photosynthesise and their leaves are often intricate to maximise the area for this process, using their green pigment to convert energy from sunlight into the chemical energy of glucose. They absorb water quickly from their environment through their thin-walled leaves and, although these can dry out speedily, they can enter a dormant state and then revive in the next downpour of rain.

The smallness of moss plants is an advantage. If their shoots grew too tall they would be exposed to the drying air of the more turbulent upper zones. Under the umbrella of forest or woodland mosses grow taller. Many have long narrow leaves to slow the air flow around them and stop them drying out, if they have humidity and shelter they can thrive in what is in some ways a miniature rain forest layer.

There still exists in Britain secret, small, temperate rain forests. They are remarkable areas of ‘Atlantic Woodland’, stretching from North Scotland to small valleys on Dartmoor where ancient woodland sustains rare species of moss and liverworts on floor and branch. The Woodland Trust website video shows how beautiful these plants are.

Moss has no flowers and therefore no seeds and its principal method of reproduction is fascinating. It reproduces by minute single-celled spores. Fertilisation can only occur in the presence of water to make it possible for the male sperm cells to swim to the female archegonia. This structure is flask-like and produces one egg.After fertilisation a zygote forms which develops into a sporophyte. This is a stem surmounted by a capsule topped by a lid. The tiny fringe of teeth inside, arranged in a double or single ring, are beautiful and varied in form. They regulate the escape of the spores when ripe as, taken by the wind, they start the lifecycle of the moss all over again if they land on a nourishing surface.

A King Penguin book shows these structures drawn in wonderful detail by Johannes Hedwig in Leipzig in 1787. By profession he was a doctor but he loved botanical research and with his early microscope observed mosses and their reproductive cycle in amazing detail.

Mosses have been on this planet for 500million years, probably evolving from salt-water algae, and they are resilient, adaptable and able to find new places to colonise. After volcanic eruption, wildfires, and deforestation mosses can spread quickly via their spores and stabilise the soil surface creating a subtle, fertile topsoil for other plants to grow in. In woods and forests they absorb water and nutrients and release them back into the ecosystem, building fertility, and providing shelter and food for many invertebrate creatures.

It was recently discovered that half a square metre of moss can absorb a huge 1kg of carbon dioxide. That’s more than a small forest!

Go to Tyrrel’s Wood, behind Long Stratton and you may find Swan’s-neck thyme moss or Glittering Wood Moss that forms yellowish-green or brown carpets with surprising bright red stems. Shady, damp woods are an ideal place to become enchanted by mosses. A hand lens is a very useful tool for beginning to marvel at them.

References                                                                    

A Field Guide to Bryophytes by Dominic Price and Clive Bealey (2022) (The Species Recovery Trust)

A Book of Mosses by Paul Richards (1950) (King Penguin Books )

British Bryological Society                  

The Woodland Trust

 

March 2024

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