Smooth and the coppery brown colour of a conker, they could easily be mistaken for just another pebble lying on the beach.

Having been transported on the tide from tropical islands to Hebridean shores, then strung on a silver necklace with a scattering of amber beads for good measure, the seeds of Entada gigas would bring peace of mind for centuries of superstitious islanders.

The power of a tiny tropical seed to protect against Hebridean witchcraft, bring good luck and shield the wearer from the threat of the ‘evil eye’ – even cure sickly cattle – would be passed down the generations and become entwined in island folklore.

While across the globe, from trees like aspen which were said to absorb fever from a cutting of a sufferer’s hair to plants with Satanic names such as Diel’s Claw and the unappealing fungus Devil’s droppings, the power of plants to heal, frighten, protect and soothe has survived for centuries in folklore, legends and superstitions.

Edinburgh Royal Botanic Gardens’ botanist Dr Gregory Kenicer has now explored the mystical and fantastical interaction between plants and people in an effort to unravel why certain plants became embedded in local superstitions, prized for their potential to bring good luck and to protect, or shunned for their devilish associations.

In a new book, Plant Magic, he points out that every culture in almost every part of the world has its own immense folkloric knowledge of the mysteries of plants.

And even though many of the mysteries have long since been ‘solved’ or magical claims dispelled for good, the fascination with plants’ mystical properties endure.

“Plants are magical things, from photosynthesis to folklore they are fundamental to human survival and culture,” he says. “Their abilities to germinate, disperse, regenerate, grow and respond to the seasons, coupled with their astonishing diversity and utility to humans, makes plants magical and miraculous by any definition.

“From Chaucer to Shakespeare and Walter Scott writers have been fascinated by plants in magic.”

For more modern Harry Potter fans, his book reveals a wand made from the wood of the strawberry tree, one of the symbols of the minor Roman goddess Cardea who guarded infants and babies, was regarded by Mediterranean cultures as helping to drive away witches and malign spirits.

While closer to home, a wand made from ash was said to protect animals and became used by Scottish cattle drivers who believed a stick made from ash would never hurt their beasts.

And when it came to spicing up the love life in a pre-Tinder world, plants would be the first port of call.

“If love needs a little push, there were many plants that were believed to help, including mint mandrake, carrot, cylcamen, purslain, valerian, navelwort, wild poppy (Papaver argemone), anemones, various orchids, maidenhair fern and basil,” he adds.

“It required immense caution, however, as the boundary between love, lust and obsession was a bit nebulous among these various plants and their supposed effects.

“Some interesting cantrips and spells from southern Scotland list numerous plants among other ingredients such as amphibians, minerals and body parts used to produce elaborate love potions very reminiscent of the work of Macbeth’s Wyrd Sisters.”

For those seeking an easy kitchen remedy for winning love, carrot root could be the ideal.

“Carrots were considered aphrodisiac,” adds Dr Kenicer. “The root was the most effective part for this, which suggests the influence of the Doctrine of Signatures if many ‘rude-shaped vegetable’ competitions are anything to go by.

“This may sound a little scurrilous, but the swollen root of Platycodon (Campanulaceae) is used even today in Korean traditional medicine for similar purposes.”

But he warns users seeking a love potion to take care. “The boundaries between love, lust and obsession are not clear. A tea made from Sesbania was reputed to be a powerful aphrodisiac whose effects would last for two days, like it or not.”

While few today might turn to a concoction of vervain for a love remedy – mixed with rue it was said to ensure your musket shot flew true as well as an effective love draught – many botanical-based superstitions and rituals of the past remain.

“South Queensferry’s ‘Burry Man’ is coated with the burrs from Burdock,” adds Dr Kenicer. “To this day he is led through the town, snagging people’s sins on the burrs and cleansing the town of its evils.”

The book highlights the many ways trees, herbs, ferns and mosses have been used in magical practices, from perhaps the best known witches’ herb Atropa belladonna or deadly nightshade, to the special role played by the fungal kingdom thanks to its reputation for deadly toxicity and hallucinogenic properties.

“From Pliny to the mediaeval herbalists, all warn of the dangers of misidentifying mushrooms, so such names as ‘meat of the goblins’ in Welsh is a fairly typical local name,” he adds.

“Tremella mesenterica is a fungus found on rotting wood and looks like an irregular mass of translucent yellow or orange ‘stuff’. This has earned it the monikers witch’s butter and faerie butter.

“Other fungi, such as the large bracket fungi borne on tree trunks, have names such as dryad’s saddle (Polyporus squamosus) and Devil’s hoof (Fomes fomentarius). The little ground-dwelling puffballs, with their clouds of dark spores, are the Devil’s snuffbox.

“Incidentally, the scientific name for one of the most common types of puffballs is Lycoperdon – literally ‘a wolf ’s fart’.”

According to Dr Kenicer, some superstitions linked to certain plants can cross thousands of miles with variations found in cultures around the world.

St John’s wort was believed to be effective against all forms of witchcraft in Scotland if you had it on your person, while hung up indoors, it was alleged to prevent lightning strike. A similar belief that it could protect against lightning is found in Holland, while in Russia, it is said to protect against rabies.

Other beliefs are more unique to certain locations.

In the case of Shepherd’s purse, a weed with a rosette of leaves, small white cruciform flowers and fruits like little hearts, there was bad news for Scots who found it indoors.

“This is a belief recorded by Roy Vickery, from Invergowrie,” he adds. “Some interpret this as the splitting fruit representing a purse spilling open and all the money (seeds) falling out.

“A more grisly take is for the fruit to resemble a head splitting open, thus presaging a violent death.

“More widely in Britain, the heart-shaped fruit was thought to represent a mother’s heart that would inevitably break when the fruit split open.”

Recently, however, Shepherd’s purse, otherwise known as Capsella, has been brought in from the cold to be intensively studied at the James Hutton Institute in, ironically, Invergowrie.

While some plants have dark, devilish names, such as Devil’s Guts, which provided a warning to farmers to be aware of its parasitic properties, others mask more sinister magical links.

“Lady’s bedstraw has a nice ecological message,” explains Dr Kenicer. “The roots help bind the sand together, and if you collect it from the machair it could destabilise the sand.

“But the plant yields a rare red colour, and a Uist woman was said to have gone out at night after being told don’t collect it.”

The consequences were dire for both parties, it seems.

“A related account suggests the woman haunted the man who had placed the ban on collecting,” adds Dr Kenicer, “such that he became terrified to go out after dark.”

Plant Magic by Gregory J. Kenicer is published by the Royal Botanic Garden Edinburgh. RRP: £12.99