Country diary: A hand lens reveals mosses’ micro-engineering | Plants


September 1962: a group of 11-year-olds armed with hand lenses, members of the school natural history club, sit around a table. The biology teacher Ken Murch, introducing us to wonders of nature that lie beyond the limits of the unaided human eye, hands us a ripe spore capsule of a moss: “Look at this, but breathe on it first.”

Sixty years later, I still carry a hand lens. Today I followed Ken’s instructions again, looking at a capsule of capillary thread-moss, plucked from a wall. A ring of tiny peristome teeth around the capsule mouth, regulating the shedding of spores, clenches and unclenches in response to moisture in my breath. Exquisite natural micro-engineering, as captivating now as it was all those years ago.

Three hundred years earlier, in 1665, Robert Hooke, an insatiably inquisitive polymath, was the first to describe and illustrate the hidden beauty of mosses, in Micrographia, commissioned by the Royal Society to provide “physiological descriptions of minute bodies made by magnifying glasses”.

Inside a spore capsule, he found “exceeding small white seeds” – moss spores invisible to the naked eye – leading him to question the prevailing superstitious notion that mosses sprang spontaneously from the “corruption” of surfaces they grew upon. He speculated, accurately, that those “exceeding small, and consequently exceeding light” seeds were “carried to and fro in the Air into every place” until they were washed down by falling drops of rain, to take root and propagate. A triumph of curiosity, fact-based science and deduction.

Silvery hairs of grey-cushioned grimmia channel dew and rain into the centre of moss.Silvery hairs of grey-cushioned grimmia channel dew and rain into the centre of the moss. Photograph: Phil Gates

He put his finger on one reason why these lowly plants, among the first to colonise dry land, have endured for 350m years and survived three cataclysmic mass extinctions. Their spores reach everywhere that wind blows, rain falls and life can survive.

August’s heat withered mosses here; September’s heavy showers revived them. Turning my hand lens on an emerald-green dome of grey-cushioned grimmia, growing on a fence post, I can see long, silvery leaf hairs that capture and channel mist and rain into its damp core. Within that miniature rainforest microcosm there will be minute animals: tardigrades, rotifers, nematodes. But I’ll need a microscope to see those, so I take a piece home.

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