Country diary: On a thundery, windless day, aerial plankton hang in the summer heat | Phil Gates

An early walk before the day becomes too hot. Thunderstorms are forecast. Distant wheat fields shimmer in a heat haze laden with insects small enough to be wafted aloft on columns of warm air: winged aphids, tiny black staphylinid beetles, and thrips , which we called “thunder bugs” when I was a child.

After several days of stifling heat, spear thistles spill soft cascades of plumed seeds, trapped among needle-spined leaves until convection currents tug them free. For a moment they hang in the still air, whiskery plumes struggling with gravity until rising thermals carry them away.

Flowering has finished for much of the flora of this grassy hillside. Hawkweeds, ragwort and sow thistle seeds, each a cypsela with a pappus of silvery hairs, are drying in the sun, waiting for a ride on a breeze.

Of all these aeronauts, goat’s beard ( Tragopogon pratensis ) surely has the most beautiful seed head, like a dandelion but as big as a tennis ball. Their ripe seeds separate at the slightest touch, but the plant parachutists under their filigree canopies are too heavy to stay aloft for long on this windless morning. Such is the lottery of airborne seed dispersal: some sink to earth after mere yards, others conquer new pastures on windy days.

At the bottom of the hill, beside the footpath, sun and a seed pod are performing a trick that recalls magic from childhood, more than 60 years ago. In the last day of summer term, our village primary school invited a magician who was a wizard at paper cutting; folding, snipping and pulling out the concertinaed pleats to reveal a row of dancers: a trick to take home for the long summer holiday.

On this dusty verge, broad-leaved willowherb ( Epilobium montanum) , a dainty wayside weed, is withering in the heat. As its pods dry, they split from their tips into four segments that gradually arch backwards, teasing out serried ranks of tiny seeds that briefly cling by the tips of their satin plumes, until a zephyr sends them dancing into the blue to join the rest of today’s aerial plankton.

And then, from beyond a towering bank of cumulonimbus on the horizon, a ta-da drum roll, the distant rumble of thunder.

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