Dense stands of Britain’s most common Fern, Pteridium aquilinum, bracken, carpet the floor of the woodlands near where I live, marking the progress of the year. Their tightly curled fronds appear in spring, slowly but inexorably unfurling into three large, triangular fronds which wave and susurrate in the summer breeze before dying back in the autumn to leave a rusty brown matting.

Sculptural, dramatic, primordial they may be, but the fronds of bracken are also poisonous, packed full of Ptaquiloside, up to 0.8 percent of their dry weight some studies suggest, which can cause haemorrhagic disease and bright blindness in livestock and oesophageal and gastric cancer in humans. The Koreans, though, have been able to make gosari, bracken, a principal ingredient in bibimbap, a classic and delicious staple of their cuisine, by simply boiling the fronds which breaks down the toxins.

Bracken has long been a source of fascination. The stem, when sliced at an angle, reveals a pattern, known as the devil’s hoof in Scotland, but which many saw as representing the Greek letter chi, the initial of Christ. From this sprang the belief that it provided protection. Waving a frond in front of a witch was enough to ward off her spells and send werewolves and other evil spirits packing. In Brittany and Normandy shepherds used crosses woven from ferns to safeguard themselves and their flocks while in Slavic countries, to drive away Rusalki, freshwater sirens with a penchant for drowning mortals, bathers entwined ferns into their hair before taking a plunge into a lake.

And how did the fern, which has no discernible flower or seed, propagate itself? After all, as the French botanist, Joseph Pitton de Tournefort, wrote in 1694, “the views of those who believe all plants have seeds are founded on very reasonable conjectures”. As plants, ferns must have flowers and seeds. The only logical conclusion was that they bloomed and produce their seeds when no one was around to see them.

It was believed that what the pastoral poet, William Browne, described as the “wondrous one-night seeding ferne” in Britannia’s Pastorals (1613) took place on the stroke of midnight on Midsummer’s Eve or St John’s Eve. Conveniently, it was not only the shortest night of the year but also the exact moment that John the Baptist was said to have been born. The fern would produce a bright red flower that lit up the woods only to be immediately snatched by the devil.

Others thought it was blue, always tricky to be sure when you have never seen it, while in Polish folklore the bloom would last until the first cockerel had crowed in the morning. According to some traditions, those lucky enough to find fern seeds would have all their wishes come true, while in England their possession brought success in love. Youths would go to Boggart Hole Clough near Manchester in search of the “seeds of St John’s fern on the Eve of St John’s Day” to win the hearts of those maidens who had previously spurned their advances.