Country Diary: A quiet autumn for acorns so far – but this oak tree is being productive

As darkness narrows the days, I increasingly crave the sun. However, today's irresolute weather is typical of this liminal season. I began my walk in sunshine and now the air plumes with drizzle. Meanwhile, further along the River Lagan, slanted rays are breaking through the cloud.

At the bank of the river, faded umbellifers sieve the gauzy light, but it's the soft flowers of bindweed that hold my gaze. Parts of the slope are loosely dressed with other blooms: clumps of oxeye daisy, dabs of vetch and bird's-foot trefoil. The sun briefly highlights a pallid insect tipping the cerise petals of Himalayan balsam. It's a common carder bee , grizzled with age. It lurches away, leaving me feeling edgy, unsure if I'm in the middle of summer's linger or spring's advance.

Turning for the woods that wear their autumn colours as lightly as a borrowed shawl, I'm greeted by a jay's screech. This colourful corvid, with its penchant for acorns, has had slim pickings this year. I shuffle the leaf litter and scan the twigs. Any fallen acorns have long been hoovered up by the jays and grey squirrels, but I struggle to find the inedible part of an oak's fruit, the acorn's cupule.

In terms of acorn production, oak species cycle through periods of boom and bust. During a mast season, trees produce a bumper crop, overwhelming the ability of acorn consumers to devour the bounty. This allows more acorns to survive and germinate. However, masting expends a lot of energy and is usually followed by decreased productivity for a few years. Oak masts were recorded in 2022 but, after a wet spring and washout summer , this looks like a bust year.

Nevertheless, one tree has produced a crop. I crouch down at the glistening mass that sprouts from the trunk's base. These dainty mushrooms are the fruiting bodies of the clustered bonnet fungus, Mycena inclinata , an oakwood specialist. With their indented margin, the "bonnets", or caps, are like miniature parasols. It's a resemblance that is grimly, if ironically, apt. For these are the fruits of decay that ripen without the sun.

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