After explaining to a visitor the lengths to which I go to encourage marsh and spear thistles on my fen, I was amused to hear her describe the troubles she takes to keep them from her garden. I know they’re prickly customers, but why do people dislike them?

What I cherish most is the sheer architectural grandeur of the summer plant. Each fully open flowerhead has a kind of declarative beauty – a blend of spine-fringed awkwardness and inner sensuous velvet. No wonder nations have hitched their wagons to the thistle’s star-like bloom. Even in autumn, when they are desiccated and devoid of seed floss, and possibly enwrapped in old spider’s web, they retain an aura of dignity.

Yet my real awakening to their virtues was thanks to the bumblebees. I love these insects, and they, in turn, adore feeding on thistle blossom. There are few more impressive summer sights in our area than a marsh-thistle bed in a late-June blow. Scores of the magenta-topped spikes bend back and forth in the breeze like some kinetic sculpture. Regardless of this fair-ride movement, the bees cling to those bulbous heads or dance from one swaying wand to another.

My favourite recent visitor to Blackwater’s thistles is a Megachile leafcutter bee. It gathers the pollen, not in a sac on the hind leg as in bumblebees or honeybees, but on specialised hairs across the whole underside of its abdomen.

Megachile bees can swim sometimes for minutes on end through those plush beds in a big spear-thistle head. They also use their legs to press the pollen from the scores of individual florets until they utterly smothered in the stuff.

To watch them about this business, truffling head-first in the plants’ sexual parts, one senses that there is an almost ritualised, erotic pattern to the movements. It is as if the insect realises that it’s an agent in the thistles’ reproduction.

There is mutual profit in the process, because more pollinated flowers means more plants next year – and more thistles means more bees. At Blackwater this insect is truly propagator-in-chief in its own garden.

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