Tree Of Life

In the last of his occasional series on gardens, nature and serendipity, the writer and broadcaster Richard Mabey reflects on how all life, from simple slime mould to riotous grandchildren, has a role to play in the improvised drama of his Norfolk garden

- Richard Mabey

Most early autumns a curious yellow curd appears scattered across our meadow. The patches are frothy and shapeless and look more like some excremental fall-out than anything living. It’s called ‘dog-vomit’ fungus, but that is an insulting misnomer. I prefer to be reminded of lightly cooked scrambled egg. And it’s not a fungus or even a plant, but a slime mould, a kind of organism that is now on a branch of its own on the great Tree of Life.

Slime moulds are truly astonishing creatures. They spend much of the year as a swarm of microscopic, single-celled organisms browsing on yeasts and bacteria. Then in the autumn, or whenever there is an abundance of food, the cells come together and form the communal yellow splodges. At this point the aggregates metamorphose into something resembling a fungus, putting up fruiting bodies and dispersing cell-rich spores, so that the whole cycle begins again.

They have one other extraordinary property. During aggregation they form critically efficient channels between sources of food. In one recent experiment, scientists laid out oat-flakes (a favourite slime snack) in the geographical disposition of the stations on the Tokyo underground system. The slime-mould swarm scoped the whole area, then gradually began to refine the links between the flakes (along which food is shared) to echo the tracks of the underground train lines, sometimes finding even more direct links.