Why mushrooms choose to fruit remains mysterious

ANOTHER LIFE:THE WARMTH of Connacht's long, dry spring was stored with particular benefit in the sandy undulations of the machair, the west's distinctive habitats of lawn-like turf behind the seashore, dusted by winter gales with limy seashell fragments and brightly carpeted just now with patches of purple wild thyme.

A neighbour who went fishing for mackerel on the headland came upon hundreds of field mushrooms in snowy arcs and circles on the turf. “It was strange,” he reported, “seeing mushrooms growing literally feet from the ocean.” Summer visitors brought us a big bag of them, gathered on the flat machair behind the dunes.

All this sent me out at dawn last week with dog and knapsack. It is most of 20 years since we had a really good mushroom summer – 1992 in the archives, with our first feast on July 10th. Weeks of sun, I noted then, had been followed by "days of silky drizzle from the sea" – conditions traditionally favourable for summoning the fruits of Agaricus campestris.

This time it took a repeated, but welcome, hammering of showers on the salty lawn of the duach. Rather like the flowering of some kinds of orchid, predicting when and why mushrooms choose to fruit remains quite mysterious: mycologists still juggle with the interplay of temperature, moisture and nutrient supply.

The “fairy rings”, at least, are readily explained, as the fungus’s underground network of mycelia, exhausting the soil’s nutrients year by year, spreads out slowly to find more food. At the network’s leading edge, the breakdown of organic food releases nitrogen, enough for the filaments’ own sustenance, but also nourishing an extra growth of grass – hence the vivid ring of green in which the fungal fruits appear to shed their reproductive spores.

One circle that served our breakfast was about 10m across, nourished over time by the droppings of sheep and rabbits. One might think these to be fairly evenly scattered but their distribution is complicated by the advance of high spring tides. The water swirling in behind the dunes lifts the raisin-like droppings and gathers them at a dense and wavy tideline on the grass around the fairy rings. Other fungal species, it seems, have a less provident time of it: the largest ring currently on record has been created by a bootlace fungus beneath almost 9sq km of a forest in Oregon and is reckoned at some 8,500 years old.

I gathered that nugget from fungus.ie, a website reflecting the new and energetic promotion of interest in Ireland’s wild mushrooms, notably those of the island’s woodlands. It is sponsored by Coford, the government-funded National Council for Forest Research and Development. This agency has also published the best photographic guide to the 43 edible mushroom species that grow in Ireland and 27 others that are best – sometimes imperatively – left alone.

Gathering woodland mushrooms beyond a handful of species that are readily learned as safe and delicious (wood hedgehog, chanterelle, penny bun, wood blewit, are examples) needs sober identification and a hobbyist’s passion for detail. It goes beyond scrutiny of stipes, gills and cap colours to discerning the sometimes subtle scents of mushrooms, and even to making overnight spore prints at home.

But the authors of Forest Fungi in Ireland(€30 hardback and ring-bound, go to coford.ie or pubsales@opw.ie) are still mad keen to spread the word. One of them, Louis Smith, is a culinary arts lecturer at Galway-Mayo Institute of Technology, a self-taught mushroom expert whose mission is to put wild and edible Irish fungi into the kitchens of every good chef in the land. Across the mountain at Delphi House, for example, bowered in old, fungus-rich (and jealously private) woodland, the chef distils the chanterelles into little cupfuls of intense and memorable flavour.

The mutually beneficial (mycorrhizal) relationships of fungi with the roots of particular groups of trees is part of the lore of mushroom-hunting and one good reason why ceps, chanterelles and so on don't lend themselves to commercial cultivation. While old broadleaved woodlands are generally the most productive, especially of the tasty white hedgehog fungus, Hydnum repandum, a good range of edible species also associate with conifers. A survey for Coford in 2007 found the big and highly prized penny bun, or cep ( Boletus edulis), found mainly with oaks on acid soils, growing at two sites of Sitka spruce.

Such surveys, repeated in subsequent year by Tom Harrington and Maria Cullen, are testing the potential of wild forest fungi as “a secondary forest product” and natural resource. This autumn will see the final visits to more than 50 sample forest sites spread across the Republic. At the height of the tiger years, we were importing €1.4 million worth of fresh and frozen wild mushrooms, mostly for restaurants and hotels. Now may be a time for gathering our own.

Eye on nature

A duckling swam out from cover into the middle of the river at Ballsbridge and dived underwater. Then a large heron appeared, landed just where the duckling had dived, flapped around until he caught it and made off with it in his beak, leaving the mother lost.

David Clarke, Clontarf, Dublin, 3

Fishing Lough Vearty in south Co Donegal, I waded about 10m across to an island. When I turned I saw a small animal with its bushy tail floating behind swimming towards me. It took a brief breather on a small rock right beside me, then panicked and dashed across the water to safety. It was a red squirrel.

Eckhardt Schmidt, Letterkenny, Co Donegal

I recently harvested broccoli from my allotment and left it in the fridge. When I took it out a few days later I found a large, brown caterpillar on it which I placed outside as it was still alive. It was about 4.5cm long.

Fiona Durcan, Donabate, Co Dublin

You were being kind to the unwelcome cabbage moth caterpillar, which could decimate your brassicas.

I see a juvenile seal basking regularly at the Sean O’Casey Bridge on the Liffey.

Barry Devon, Mayor St, Dublin

There have been several reports of leucistic grey crows with white patches.

Michael Viney welcomes observations at Thallabawn, Carrowniskey PO, Westport, Co Mayo. viney@anu.ie. Please include a postal address