The strange, amazing stories behind six everyday plants

Often beautiful, sometimes deadly, but constantly ingenious, plants are the sources of life and delight, myth and mayhem.

Their worlds are intricately entwined with our own history, culture and folklore. Some have a troubling past, while others have ignited human creativity or enabled whole civilizations to flourish.

Here are a handful of the stranger stories behind the plants you see every day.

Tomato

Cheerful yellow tomato flowers, shaped like a wizard’s hat, need to be shaken to release their pollen. They resonate with the buzzing of bumblebees’ bodies as they clamp themselves to the flower and flex their wing muscles at a middle-C buzz, a noticeably higher pitch than the humdrum beat of flight, and just right to dislodge the pollen. Most commercial greenhouses employ captive bumblebees to perform this service.

Tomato flowers are not the only part of the plant that responds to vibration. Researchers in Korea recently found that if they played loud sound to harvested tomatoes (this time a high C, for six hours), ripening was delayed – by as much as six days. Astonishingly, the vibrations seem to affect the way the fruit manufactures its ripening hormones.

Having introduced tomatoes to Europe from Mexico, Spain has taken the fruit to heart. The pinnacle of their tomato pride is La Tomatina, a summer festival held near Valencia. It is a very Spanish entertainment. Lorries dump thousands of tonnes of overripe pulpy tomatoes in the central square and two teams (we use the term loosely here) hurl them at each other in a physical, and extraordinarily sensual, scarlet orgy. Seeing so much tomato, it is hard not to think of the conquest of Central America, and of blood too.

Prickly pear

The prickly pear cactus is of sufficient cultural significance to appear at the centre of Mexico’s flag. The reason lies with a little sap-sucking scale insect, the cochineal (Dactylopius coccus), that thrives almost exclusively on the pads of prickly pears. The sap they suck is colourless, but they manufacture and store in their little bodies an improbably lurid red chemical, carminic acid, which is their defence against ants, birds and mice.

At least 2,000 years ago, the people of Central America had learned to farm the insects and were using cochineal to colour their textiles. When Spanish invaders arrived in the 1500s, they were astounded; red dyes in Europe were more muted, hideously expensive and tricky to use. It’s small wonder then that cochineal became an export earner second only to silver and gold.

Cochineal scarlet entered the realm of royalty and luxury; for renaissance professionals a scarlet turban or cloak were signals of success and in the early 19th century, it was used to dye the stripes of the original “star-spangled banner”, inspiring the US national anthem. By 1900, synthetic dyes had replaced cochineal for textiles, but health concerns about artificial additives have encouraged a renaissance in sweets, soft drinks and lipsticks.

Pineapple

Pineapples caused a sensation in Europe after Christopher Columbus returned from the Caribbean in 1496 with one that had miraculously survived the journey. Endorsed by royalty, exotic, fabulously difficult to obtain, and unencumbered by biblical associations, they came to signify nobility, wealth and impeccable taste.

Perhaps because of their association with class, pineapples became a peculiarly British fixation. By the mid-18th century, a few plants had finally been coaxed into fruiting by aristocrats with money to burn on gardeners, coal and glasshouses. Far too expensive to eat, their

Even the word pineapple was associated with excellence. In the 1770s, the diarist James Boswell described the luxury of receiving a letter during a tour of the Scottish Hebrides as being “a pineapple of the finest flavour”. The fruit inspired the design of fine Wedgwood pottery, a profusion of architectural ornaments, and occasionally, whole buildings.

Liquorice

A chest-high, bushy shrub, liquorice originated and grows wild in Eurasia and the eastern Mediterranean. Used medicinally since ancient times, by the 14th century liquorice had become synonymous with sweetness and agreeable odour, rare and desirable qualities in those days. In his Canterbury Tales, Chaucer wrote of a clerk “himself as sweete as is the roote of lycorys” and a courting lover who “first cheweth … lycorys to smellen sweete”.

Our association of liquorice with sweetness, or at least contentment, is so intense that it is hard to believe it could be harmful, but its active constituent, glycyrrhizin is far from benign. Eating just a handful of black liquorice a day for a fortnight can interfere with some of the body’s hormone systems and cause high blood pressure, heart arrhythmia and muscle weakness. The medical consensus is to limit daily consumption to the weight of an egg, and certainly not every day, since it is slow to clear from the body.

In Scandinavia, where liquorice is especially popular, it carries health warnings. There, it is often mixed with ammonium chloride, a distinctively sharp and strangely salty chemical, and labelled as unsuitable for children.

Mexican yam

Yams are climbing vines, generally from the tropics, renowned for their often-edible tubers – swollen starchy underground stems that store nutrients and water. The Mexican yam of the country’s humid south-eastern forests flaunts strings of subtle green or pale pink flowers with bold maroon centres. Its inedible semi-buried tuber, with a corky tortoiseshell outer layer and deep, polygonal furrows contains a substance called diosgenin.

Diosgenin is part of the plant’s natural defences but for us it is a vital starting ingredient for the manufacture of a class of substances that have profound effects on the human body – steroids. They include the sex hormones progesterone and testosterone, as well as drugs to treat asthma, rheumatoid arthritis and various other autoimmune diseases.

Yam-derived diosgenin was used to produce the hormone cocktail that first used to trick a woman’s body into acting as if it is pregnant, thereby inhibiting ovulation. So, the contraceptive pill was born.

Some species of yam sustain life as a staple food while others are still cultivated to provide the basis of drugs that prevent it. Either way, it seems fitting that a plant with such splendidly heart-shaped leaves should have had such a profound effect on the wellbeing and love lives of millions of people.

Peat moss (Sphagnum)

Rarely reaching even ankle-height, sphagnum moss is the unassuming principal architect of the peat bog: a serenely beautiful habitat and one of the world’s most important ecosystems. Across the sub-Arctic, in waterlogged places where rain is frequent, sphagnum species create a moist mantle in colours drawn from a surprisingly wide palette; muted greens and subdued shades of russet, copper and chocolate are dotted here and there with bright patches of warm pinks, oranges and even yellow.

Sphagnum is remarkable in the way that it manipulates its environment to suit itself, while sabotaging competitors; its covering carpet with dangling tangles of dead leaves creates areas of stagnant water starved of dissolved oxygen; it extracts more dissolved nutrients than it needs for its own survival and sequesters them, leaving precious little for others; and its cunning chemistry makes bog water very acidic indeed – discouraging to most plants, and microorganisms too.

Unable to decay, dead sphagnum settles and, under pressure, accretes to form peat – a forerunner of coal. The deepest bogs are more than 10,000 years old but are now threatened by drainage for forestry and agriculture and by cutting for fuel or improving garden soil. This is disastrously myopic. The world’s peat bogs have captured more than twice the amount of carbon stored in all the tropical rainforests combined.

• Jonathan Drori is the author of Around the World in 80 Plants and Around the World in 80 Trees, both illustrated by Lucille Clerc and published by Laurence King. He is a former trustee of the Royal Botanic Gardens, Kew.