166 Fun Facts About Plants

What pigment gives most plants their green color?

Chlorophyll looks green because it soaks up red and blue light for energy and reflects the green wavelengths it barely uses.

What gas do plants absorb from the atmosphere during photosynthesis?

Carbon dioxide is the raw material of wood, which is about half carbon by weight; that is why van Helmont's potted tree could grow heavy in the 1600s while its soil barely lost weight.

In which part of a plant cell does photosynthesis primarily occur?

Chloroplasts began as free-living cyanobacteria engulfed by an ancestral cell, which is why they still carry their own DNA and multiply by dividing in two.

What is the main product plants create through photosynthesis?

Glucose rarely stays as glucose: the plant ships it around as sucrose, stores it as starch and strings it into cellulose, the stuff of cotton and wood.

What are the tiny pores on the surface of leaves called that allow gas exchange?

Stomata are each flanked by two guard cells that swell with water to open the pore and go limp to shut it, which lets a thirsty plant seal its leaves.

What part of a flower produces pollen?

Anthers of tomatoes and blueberries hold their pollen tight, so bumblebees grip the flower and buzz their flight muscles to shake it loose, a trick now used in commercial greenhouses.

By what process do plants lose water vapour through their leaves, drawing more up from the roots?

Transpiration lifts water without a pump: as vapour escapes the leaves, each molecule tugs on the next, hauling an unbroken thread of water up from the roots.

What type of plant tissue transports water from roots to leaves?

Xylem is what wood is made of: its water-carrying cells die as they mature, leaving the empty, stiffened tubes that both carry sap upward and hold the tree up.

What is the female reproductive part of a flower called?

The pistil is named for the pestle it resembles; once its ovules are fertilised, its swollen base, the ovary, ripens into the fruit.

What is the point on a plant stem where a leaf attaches called?

Node is also the botanist's word for a potato's 'eye': the tuber is a swollen stem, and each eye is a node whose bud can sprout a new plant.

What is the tallest species of tree in the world?

Coast redwood holds the record through Hyperion, about 116 metres tall; the park has since closed the ground around it because visitors seeking it out were trampling its base.

What is the largest tree by volume in the world?

Giant sequoia cones can stay green and shut for twenty years; the heat of a fire dries them open, raining seed onto freshly cleared ground.

What makes a Venus flytrap's trap snap shut?

Two touches in a row, within about twenty seconds, tell the trap that something alive is walking inside; it then counts several more before it starts to digest.

Which carnivorous plant uses a pitfall trap filled with digestive fluids?

Pitcher plants are not always killers: one mountain species feeds tree shrews at its lid and collects their droppings, which supply most of the nitrogen in its leaves.

What is the part of a seed that develops into the new plant?

The embryo is a complete miniature plant held dry and dormant; when the seed soaks up water it swells, splits its coat and the embryo's root pushes out first.

White flour is milled from which starchy part of the wheat grain?

Endosperm is the grain's own food store for the sprouting plant; millers strip away the bran and the oily germ, which would turn flour rancid, and keep the starchy white core.

Monocots are named for having a single what?

Seed leaf is the plain name for a cotyledon: monocots have one and dicots two, which is why a bean or peanut splits so neatly into halves.

What do we call trees that drop all their leaves each year, usually in autumn?

Deciduous trees such as oaks, maples and birches shed all their leaves in autumn to cut water loss in the cold or dry season; the word comes from Latin decidere, 'to fall off'.

What is the largest individual flower by diameter in the world?

Rafflesia arnoldii has no leaves, stem or roots of its own: it lives hidden inside a vine and shows itself only as a metre-wide bloom that reeks of rotting meat to draw flies.

What type of plant reproduces via spores rather than seeds?

Ferns shed dust-fine spores from the brown dots under their fronds: each dot is a cluster of spore cases, and a ring of cells around each case flings the spores into the air.

Which climbing plant's cone-like flowers give beer its bitter flavour?

Hops replaced 'gruit', the mix of bitter herbs that earlier brewers relied on, and they do more than flavour beer: they also help it keep.

Which insect is shipped across America in rented hives each February to pollinate California's almond orchards?

Honeybee hives are rented because the vast almond orchards need far more pollinating insects than live nearby; it is the biggest managed pollination event in the world.

What is a plant that completes its entire life cycle in one growing season called?

Annual plants live on only as seed: the field poppy dies each year, but its long-lived buried seeds sprout when the soil is turned, which is why poppies flare up in ploughed fields.

What ecological role do plants play as the base of most food chains?

Producers trap the sun's energy, but only about a tenth of it passes up each link of a food chain, which is why food chains are so short.

What is the symbiotic relationship between fungi and plant roots called?

Mycorrhiza is a trade: the fungus's fine threads reach soil that roots cannot, bringing back water and phosphorus, and the plant pays with a share of the food it makes.

Which growing method, used for greenhouse lettuce and tomatoes, raises plants with their roots in nutrient-rich water instead of soil?

Hydroponics was coined in 1937 from the Greek for water and toil, after its promoter William Gericke found his first choice of name, aquiculture, was already in use for raising aquatic life.

Cinnamon sticks are made from which part of a tree?

Inner bark is peeled from young shoots that sprout after the tree is cut back to a stump; as the strips dry they curl by themselves into the familiar quills.

What is the process of growing a new plant from a cutting of an existing plant?

Vegetative propagation keeps a variety true: apple pips grow into something different from the parent, so every Granny Smith tree is a copy descended from one chance seedling found in 1868.

Which biome has the greatest diversity of plant species?

Tropical rainforest grows on surprisingly poor soil: heavy rain leaches the nutrients away, so the forest lives on fast recycling of its own litter, and cleared plots are often farmed out within a few years.

Which common herb is a member of the mint family and is widely used in Italian cuisine?

Basil is the heart of Genoa's pesto, a sauce named for how it was made: 'pestare' is Italian for pounding, since the leaves were crushed by hand in a mortar.

Which part of the saffron crocus is picked to make the world's priciest spice?

Stigmas are all the saffron crocus yields: three red threads per flower, plucked by hand, so a single pound of the spice takes tens of thousands of blooms.

Which poisonous plant is also called belladonna, said to recall Italian women who used it to widen their pupils?

Deadly nightshade's active drug, atropine, still does that job: eye doctors use it to dilate pupils, and soldiers carry it in autoinjectors as a nerve-agent antidote.

What toxic compound is found in high concentrations in rhubarb leaves?

Oxalic acid in rhubarb leaves can harm the kidneys if enough is eaten, which is why cooks trim away every scrap of leaf blade and use only the stalks, which are safe.

What structural adaptation allows cacti to survive in arid environments?

Cacti rely on water-storing fleshy stems: unlike many succulents, most hold water nowhere else, and their leaves have shrunk to spines that shade the stem and slow the drying air around it.

What name is given to plants, such as air plants, that perch on trees without feeding on them?

Epiphytes only borrow a perch: an air plant drinks rain and mist through scales on its leaves, which is why it grows just as happily on a telephone wire.

Mangroves and glassworts are called halophytes because they thrive despite high levels of what?

Salt is handled in plain sight: red mangroves keep most of it out at the roots, while other species push it out through their leaves, where it dries into visible crystals.

What is the waxy, waterproof coating on the outer surface of plant leaves called?

The cuticle is why water beads up and rolls off a leaf, taking dirt with it; some leaves do this so well that engineers copy them to make self-cleaning paints and fabrics.

Which plant hormone gathers on a shoot's shaded side, making it bend toward the light?

Auxin makes the cells on the shaded side stretch faster, so the shoot curves toward the light; Darwin and his son found the signal comes from the very tip, since capped seedlings did not bend.

What root adaptation lets red mangroves breathe in waterlogged coastal mud?

Red mangroves stand on arching stilt or prop roots that hold the trunk above the tide and take in air for the buried roots; black mangroves instead send up breathing tubes like straws.

What is the scientific study of plants called?

Botany grew out of medicine: when nearly every remedy was a herb, doctors had to know their plants, and Europe's first botanic gardens were planted at universities to train them.

Which Christmas evergreen is a parasite, rooting into tree branches to take their water and nutrients?

Mistletoe travels from tree to tree by bird: its berries are so sticky that birds wipe the seeds off their beaks onto a branch, where the glue holds them until they root.

Which 'living fossil' tree, the last surviving species of its family, has fan-shaped leaves?

Ginkgo biloba is famously tough: six ginkgos growing between one and two kilometres from the Hiroshima bomb were charred but survived and soon grew back.

Which tree species includes Methuselah, a California tree over 4,600 years old?

Bristlecone pine owes its long life to hardship: on cold, windswept slopes it grows so slowly that its dense, resinous wood resists insects, fungi and rot for millennia.

What class of plant pigment gives autumn leaves their orange and yellow colors?

Carotenoids are in the leaf all summer, hidden by the green; when that pigment breaks down in autumn they show through, while the reds come from anthocyanins.

Which Seychelles palm bears the largest seed in the plant kingdom?

Coco de mer means 'coconut of the sea' in French: hollowed-out nuts drift on the ocean, but a fertile one is too dense to float, which is why the palm grows wild on only two Seychelles islands.

What fast-growing plant can grow up to 91 cm (36 inches) in a single day?

Bamboo can do it because a new shoot emerges from the ground at its full width and reaches its full height within a single growing season, after which it never grows taller.

Which desert succulent, nicknamed the century plant, flowers just once after ten years or more and then dies?

Agave pours years of stored energy into a single flower stalk several metres tall and then dies; tequila makers cut that stalk off early so the energy stays in the plant's heart.

Which gas, given off by ripening bananas, acts as a plant hormone that hurries nearby fruit to ripen?

Ethylene is the truth behind 'one bad apple spoils the barrel': an overripe fruit gives off the gas, which pushes its neighbours to ripen and age faster too.

What nitrogen-fixing bacteria form nodules on the roots of legumes?

Rhizobium bacteria live in the root nodules of beans, peas and clover, turning nitrogen from the air into ammonia the plant can use, which is why farmers rotate legumes to enrich the soil.

The titan arum, or corpse flower, is endemic to rainforests on which Indonesian island?

Sumatra's titan arum warms the tip of its spike to about body temperature, which helps its rotting-meat scent rise and spread to the insects that pollinate it.

Aspirin is a lab-made relative of salicin, a painkiller first extracted from which tree?

Willow, Salix in Latin, gave salicin and salicylic acid their names; in 1897 chemists at Bayer produced a stable acetylated version, which the firm sold worldwide as Aspirin from 1899.

The titan arum's towering bloom is not a single flower but the world's largest unbranched what?

Inflorescence means a cluster of flowers: the titan arum's small true flowers, male above female, are hidden at the base of its spike inside what looks like one huge petal.

Which African desert is home to Welwitschia, a plant that grows only two leaves?

The Namib's Welwitschia never sheds its two leaves: they keep growing from the base for centuries while the weather splits and frays the tips into a tangle of ribbons.

Which fig tree drops aerial roots that thicken into extra trunks, letting a single tree spread like a small forest?

Banyan trees can outlive their own trunks: the Great Banyan near Kolkata had its diseased main trunk removed in 1925 and still thrives on its many prop-root trunks.

Which conifer, nicknamed the 'dinosaur tree', was unknown to science until explorers found a grove in a Blue Mountains canyon in 1994?

Wollemi pine grows wild in a single canyon whose location is kept secret, because visitors could trample seedlings and carry in disease; one water mould has already reached the site.

Utah's Pando is a single giant clone of which tree?

Quaking aspen spreads by sprouting new trunks from its roots, so Pando's tens of thousands of stems are a single organism; fences now protect its young shoots from browsing deer and elk.

Which compound gives chilli peppers their heat?

Capsaicin burns mammals but not birds, whose version of the receptor does not respond to it, so birds eat the fruit freely and scatter the seeds.

Silkworms feed almost entirely on the leaves of which tree?

Mulberry trees were planted under James I to found an English silk industry; the venture failed, and tradition blames his choice of the black kind, since silkworms do best on white mulberry.

Which fruit wears its 'seeds' on the outside, each one technically a tiny fruit of its own?

Strawberry flesh is not the true fruit but the swollen base of the flower; the real fruits are the dry specks on its skin, each with a single seed inside.

The General Sherman tree, the world's largest by volume, is named for a general from which war?

American Civil War general William Tecumseh Sherman lost the honour for a few years: a socialist colony that held the land renamed the tree for Karl Marx until a national park was created there.

Which two countries produced the most sunflower seeds in 2022?

Russia and Ukraine grow about half of the world's sunflower seed, which is why the price of sunflower oil jumped sharply around the world when Russia invaded its neighbour.

A sunflower head's seed spirals usually come in counts from which sequence?

Fibonacci numbers appear because each new floret grows about 137.5 degrees round from the last, the so-called golden angle, which makes the seeds fall into interlocking spirals.

The flame-streaked petals of Semper Augustus, tulip mania's costliest bulb, were later traced to what cause?

A virus spread by aphids 'broke' the petal colour into flames, but it also weakened the bulbs with each generation, which is why Semper Augustus no longer exists.

Tulips reached western Europe in the 1500s from the gardens of which empire?

The Ottoman Empire's sultans grew tulips in great beds, and an envoy to their court is often credited with sending the first bulbs west; the name is thought to come from a Turkish word for a turban, which the bloom was said to resemble.

Six of the eight baobab species grow only on which island?

Madagascar: a 2024 study sequenced all eight baobab species and argued the island is the genus's centre of origin, which would mean the famous African baobab's ancestors crossed the sea from there.

Baobab fruit is rich in which vitamin?

Vitamin C: weight for weight the dry pulp beats oranges for it, so once the European Union cleared the fruit as a food in 2008 it began turning up in smoothies and cereal bars.

Digitalis, a heart drug used since the 1700s, is made from the leaves of which tall garden flower?

Foxglove was one ingredient in a folk remedy for dropsy until William Withering singled it out and published his trials in 1785; the same plant that steadies a failing heart can kill if eaten.

In 2005 the Venus flytrap was designated the state carnivorous plant of which state?

North Carolina, the flytrap's main wild home, made digging one up a felony in 2014 after years of poaching on its coastal plain.

The touch-sensitive Mimosa pudica, whose leaves fold when brushed, belongs to which plant family?

Fabaceae (pea/legume) is the family: when touched, cells at the base of each leaflet suddenly lose water pressure and the leaf collapses, a reflex that may have evolved to put off grazing animals.

Kudzu first reached the United States at the 1876 Centennial Exposition, a world's fair held in which city?

Philadelphia: Japan planted kudzu in its garden at the Centennial Exposition, and Americans took to it as a shade vine for their gardens long before it ran wild across the South.

Which oily compound in poison ivy sap causes its itchy rash?

Urushiol binds to proteins in the skin, and it is the immune system's attack on those altered proteins that brings the rash; the same oil is in poison oak, poison sumac and mango peel.

The deadly manchineel tree takes its name from the Spanish word manzanilla, meaning what?

Little apple: the fruit looks like a small apple, but the tree's milky sap blisters skin on contact, and Spanish speakers now call it the 'little apple of death'.

Wolffia, the world's smallest flowering plant, belongs to which group of floating pond plants?

Duckweeds: Wolffia, or watermeal, is a rootless green speck less than two millimetres long, yet people in Thailand eat it as food.

After a peanut plant's flowers fade, where do its young pods go to ripen?

Underground: each fertilised flower sends down a stalk, the 'peg', that pushes the young pod into the soil, which is why the plant is also called the groundnut.

Carl Linnaeus published the first edition of Systema Naturae in 1735 while studying abroad in which country?

Netherlands: Linnaeus went there in 1735 to finish his medical degree at Harderwijk and stayed three years; the first Systema Naturae was a slim pamphlet that later grew into a multi-volume work.

Which system did Carl Linnaeus apply to every known plant in his 1753 book Species Plantarum?

Binomial nomenclature gives each species a two-word Latin name, such as Rosa canina for a wild rose, in place of the sentence-long descriptions botanists had used before.

Which plant did Gregor Mendel crossbreed by the thousand to work out the basic laws of heredity?

Garden pea: Mendel raised and crossed thousands of them in his monastery garden between 1856 and 1863, but his 1866 paper went largely unnoticed until 1900, sixteen years after his death.

What did Mendel call a trait that masks its rival in the first generation?

Dominant: crossing yellow- and green-seeded plants gave only yellow seeds, yet green returned in a quarter of the next generation, proving the hidden trait had never been lost.

Mendel was abbot of an abbey in which city?

Brno, then called Brünn in Austria's Moravia, is where Mendel became abbot in 1868; the job, and a decade-long tax fight with the government, ended his plant experiments.

Which spongy bog plant, able to hold many times its own weight in water, slowly builds up into peat?

Sphagnum moss holds so much water in its cells that it was once packed onto wounds as a dressing, and because it barely rots, its dead layers pile up into peat.

Cloves, the spice, are which part of a tropical evergreen tree?

Flower buds: pickers take them just before they open and dry them hard, and the nail-like shape gave the spice its name, from the Old French clou, a nail.

Which Asian city's Botanic Gardens, cradle of Malaya's rubber boom, joined UNESCO's World Heritage list in 2015?

Singapore: director Henry Ridley, nicknamed 'Mad Ridley' for his zeal, devised a way to tap rubber trees without killing them, and Malaya went on to become the world's top producer.

Victoria boliviana, named in 2022, is the largest known kind of which plant?

Water lily: its floating leaves can exceed three metres across, and it took DNA tests on plants raised from Bolivian seed to show it was a third species, distinct from the two giants already known.

On which island is the Svalbard Global Seed Vault located?

Spitsbergen was chosen for its permafrost and stable rock: the cold would keep the seeds frozen even if the vault's power failed.

In 2015 seeds were withdrawn from the Svalbard vault to rebuild a gene bank cut off by war in which country?

Syria: when fighting shut a gene bank near Aleppo, its scientists drew out their backup seeds, regrew them in Lebanon and Morocco, and later sent fresh copies back.

Where did the Nordic Gene Bank keep backup seeds from 1984, before Svalbard's seed vault was built?

An abandoned coal mine outside Longyearbyen held the frozen duplicates in a steel container; from that beginning grew the idea of a backup vault for the whole world.

In 1779 Jan Ingenhousz showed that leaves freshen stale air only when exposed to what?

Sunlight: Ingenhousz watched bubbles rise from underwater leaves in the sun and stop in the shade, which explained why Joseph Priestley's earlier experiments had given such inconsistent results.

Which enzyme, thought to be the most abundant protein on Earth, starts the Calvin cycle in plants?

RuBisCO is a painfully slow worker, handling only a few molecules a second, so plants compensate by packing their leaves with it, which is how it became so abundant.

All but one species of cactus are native only to which part of the world?

The Americas: the lone exception, the forest cactus Rhipsalis baccifera, also grows wild in tropical Africa and Sri Lanka, perhaps because birds carried its seeds across the Atlantic.

The cardón, the tallest living cactus, is native to the deserts of which country?

Mexico: in Baja California the cardón can take root on bare rock, because bacteria living in its roots dissolve the stone and free the minerals it needs.

Which Sonoran Desert cactus can take more than half a century to sprout its first arm?

Saguaro: its growth depends on rainfall, so the first arm appears after 50 to 75 years in wetter spots and closer to 100 in dry ones, and some plants never branch at all.

Orchidaceae is one of the two largest families of which plant group?

Angiosperms are the flowering plants, and this one family supplies some 28,000 of their species; some of its flowers mimic female wasps so well that the males try to mate with them.

Seeds of which aquatic plant sprouted in the 1990s after about 1,300 years in a dry Chinese lakebed?

Sacred lotus: carbon dating put the seed at roughly 1,300 years old, and the tough coat that seals each one is thought to be a main reason it stayed alive so long.

Arabica, the world's main coffee species, grows wild in the highlands of which country?

Ethiopia: arabica arose in its south-western highlands as a natural cross between two other coffee species, one of them robusta, the more bitter, more caffeinated bean that is now its chief rival.

Wheat was first farmed more than 10,000 years ago in which region?

The Fertile Crescent, the arc of farmland from the Levant to Iraq, gave the world wheat; bread wheat itself appeared later, when emmer crossed with a wild goat grass in farmers' fields.

Genetic studies trace the cultivated potato to a single origin in which region?

Southern Peru and north-west Bolivia is where potatoes were first domesticated, yet almost every variety grown worldwide today descends from a later lowland strain from south-central Chile.

Botanically, what kind of fruit is a banana?

A berry, botanically, is a fleshy fruit grown from a single ovary with its seeds inside, which lets in bananas, grapes and tomatoes but shuts out raspberries and blackberries.

Which banana variety took over world exports after Panama disease devastated the Gros Michel in the 1950s?

Cavendish plants resisted the fungus that ruined Gros Michel plantations, but because every one is a clone, a newer strain of the same disease now threatens them in turn.

Botanically, the coconut is what type of fruit?

A drupe, like a peach or an olive: a fibrous husk wraps a hard stone that holds the seed, but while we eat a peach's flesh and throw away the stone, with a coconut we do the reverse.

Which three countries produced the most coconuts in 2024?

Indonesia, India and the Philippines grew nearly three-quarters of the 2024 crop; the thick-husked wild fruit can float to new beaches, and seafaring settlers carried the palm far beyond its home shores.

Bamboos belong to which group of plants?

The grass family, Poaceae, includes the bamboos, and like other grasses they have no wood-forming growth layer, which is why a bamboo stem is a straight column that never thickens with age.

Which Christmas plant's showy red 'petals' are really leaves, with its true flowers the tiny yellow dots at the centre?

Poinsettia 'petals' are bracts, leaves that colour up to do a flower's advertising; the plant is named after Joel Poinsett, a 19th-century American diplomat who sent specimens home.

Which three species of Cannabis are sometimes recognised?

Sativa, indica and ruderalis are the three species sometimes recognised, though other botanists fold them all into one variable species; hemp is the name for varieties grown for fibre and seed rather than drugs.

Which three countries grew the most tea in 2022?

China, India and Kenya led the world in 2022; India's plantations got a boost in 1848, when the East India Company sent Robert Fortune into China to bring out tea plants and skilled tea makers.

Which is the most oxidised type of tea?

Black tea is fully oxidised: the leaves are withered, rolled and left to darken in the air before heating, whereas green tea is heated straight away to stop that reaction.

Edmond Albius, an enslaved 12-year-old, worked out in 1841 how to fertilise by hand the flowers of which spice plant?

Vanilla flowers have a flap that keeps them from setting pods unaided, so Albius lifted it with a thin stick and pressed the parts together with his thumb, a move growers on Réunion and far beyond still repeat.

Vanilla comes from the cured seed pods of which family of flowering plants?

Orchids of the genus Vanilla are climbing vines whose pods are picked green; the famous flavour is not there at harvest but develops as the pods are cured.

What does the cacao genus name Theobroma mean in Greek?

Food of the gods is how Linnaeus styled cacao in 1753, and the name passed to theobromine, the chocolate stimulant that people clear quickly but dogs break down too slowly to eat safely.

Which country was the largest producer of cocoa beans in 2022?

Côte d'Ivoire grew about two-fifths of the world's cocoa beans in 2022, far ahead of any rival, even though the cacao tree is not African at all but a New World native.

Cacao flowers grow directly on the trunk and older branches, a trait called what?

Cauliflory comes from the Latin caulis, 'stem', the root it shares with cauliflower; cacao's trunk-borne blossoms are visited not by butterflies but by tiny biting midges.

Oak galls, growths that wasps trigger on oak trees, were for centuries crushed to make what?

Ink: tannin-rich galls mixed with iron salts made iron gall ink, Europe's standard writing ink from late antiquity into the 1800s, though over time it eats into the pages it was written on.

Old Tjikko, a Norway spruce with roots about 9,500 years old, grows in which country?

Sweden: on Fulufjället in Dalarna, no single trunk has lived that long; the spruce has lasted by pushing up a fresh trunk each time the old one died.

Jōmon Sugi, a giant cedar thousands of years old, grows on which Japanese island whose forests inspired Princess Mononoke?

Yakushima: the cedar's rediscovery in the 1960s spurred the protection of the island's old-growth forest, now a World Heritage Site; its age is put at anywhere from 2,000 to 7,200 years.

The Angel Oak, a giant southern live oak, stands on Johns Island near which city?

Charleston's city government owns the Angel Oak and its park on Johns Island; the tree is far wider than it is tall, about 65 feet high with a canopy that shades some 17,000 square feet.

Which spice is the thin red coating that wraps the seed inside a nutmeg fruit?

Mace and nutmeg come from one fruit: the nutmeg is the seed, while mace is the crimson net around it, peeled off and dried until it fades to orange.

Which Mediterranean tree's thick bark is stripped every nine years or so?

Cork oak bark, the stuff of wine-bottle stoppers, grows back after each stripping, so a tree can be harvested again and again without being felled.

Black, green and oolong teas all come from one evergreen shrub that belongs to which genus of garden plants?

Camellia sinensis, the tea plant, is a cousin of the showy garden camellias; drinks brewed from anything else, hibiscus and chamomile included, are strictly herbal infusions rather than tea.

Darwin found that sundew leaves dissolve meat with a juice much like the one made by which human organ?

The stomach: after years of feeding sundews, Darwin concluded in 1875 that their leaves release acid and a 'ferment' resembling pepsin, the enzyme that breaks down protein in our own gastric juice.

Most Eucalyptus species are native to which continent?

Australia is home to nearly all of the 700-odd eucalypt species, and many are built for bushfire: after a blaze they resprout from buds protected beneath their bark.

Which Arabian Sea archipelago is home to the red-sapped dragon blood tree?

Socotra, part of Yemen, is the only place the tree grows wild; its dark red resin, called dragon's blood, was prized in the ancient world and is still used as a dye and a folk medicine.

How do Lithops, succulents of southern Africa, avoid being eaten by grazers?

Camouflaging as pebbles is in the name, from the Greek for 'stone' and 'face'; most of each plant sits buried, with only a flat, mottled window on top to let light through.

Which marine plants include Mediterranean clones thought to be thousands of years old?

Seagrasses are true flowering plants whose ancestors returned from land to the sea; a meadow of Posidonia oceanica may be a single clone that has crept outward for thousands of years.

The Wardian case, which let Victorian plant hunters ship live plants by sea, was the forerunner of what?

The terrarium grew out of an accident: around 1829 Nathaniel Ward sealed a moth chrysalis in a bottle of damp soil and found plants sprouting inside, thriving without fresh air or watering.

The common name of the yellow lawn weed Taraxacum officinale comes from the French for which animal's tooth?

A lion's tooth, 'dent de lion' in French, became 'dandelion' in English; the name describes the jagged edges of the plant's leaves, not its flower.

Which chemical do stinging nettle hairs inject like tiny hypodermic needles?

Histamine, the same chemical behind hay fever, is injected when the hollow trichomes snap off at the tip; the rash is called 'contact urticaria'.

Which icon of Western films is really a Eurasian plant that reached the United States only in the 1870s?

Tumbleweed: the plant is said to have arrived in South Dakota mixed into imported flax seed, and it spread fast because each dead bush snaps off and rolls with the wind, scattering seeds as it goes.

Which botanical fruit did the US Supreme Court rule a vegetable for tariff purposes in Nix v. Hedden?

Tomato importers lost because the justices went by the dinner table: tomatoes were served with the main course, not as dessert.

Which fruit carries its apparent seeds on the outside, each one really a tiny fruit called an achene?

Strawberry flesh is not the true fruit either: it is the swollen receptacle that held the flower, which is why botanists call it an accessory fruit.

Which snack 'nut' is really a legume whose pods are pushed into the soil to ripen underground?

Peanut plants flower above ground and then bury their own fruit, a habit so odd that Linnaeus named the species hypogaea, 'under the earth'.

Broccoli, kale and Brussels sprouts are all cultivated forms of which single coastal European species?

Wild cabbage turned into each of them as growers selected a different part: leaves for kale, side buds for Brussels sprouts, swollen stems for kohlrabi.

Apples, pears, cherries and almonds all belong to the plant family named after which garden flower?

Rose relatives fill the fruit bowl: the family also gives us peaches, plums, apricots and raspberries, making it one of the six most valuable crop families.

Which spice is the dried inner bark of a tree in the laurel family, rolled into curls called quills?

Cinnamon peelers keep only about half a millimetre of inner bark, prying it off in long strips that roll themselves up as they dry.

Which thorny 'king of fruits' is banned on Singapore's public transport because of its lingering smell?

Durian odour can hang around for several days, which is why hotels and transit systems in Singapore and Bangkok refuse to let it in.

A mature sunflower head stops tracking the sun and typically settles facing which compass direction?

East-facing heads warm up faster in the morning, and the extra warmth brings more pollinator visits.

George de Mestral invented Velcro after studying which plant's hooked seed heads stuck in his dog's fur?

Burdock burs carry hundreds of tiny hooks that catch on any loop of fur or cloth, so de Mestral copied them as one strip of hooks and one of loops.

Which Christmas plant is a parasite that roots into tree branches and takes their water and nutrients?

Mistletoe still makes some of its own food by photosynthesis, so botanists class it as a hemiparasite rather than a full parasite.

Which gas do green plants release as a waste product when they split water during photosynthesis?

Oxygen is only a by-product for the plant, yet most living things on Earth, plants included, depend on it for respiration.

The bark of which tree contains salicin, a natural forerunner of aspirin used for at least 2,400 years?

Willow bark was recognised as a fever and pain remedy in the 1700s, after an English clergyman who thought it tasted like medicinal Peruvian bark tried it on local people for five years.

Tequila is distilled from the baked core, or piña, of which spiky Mexican succulent?

Blue agave cores can weigh 70 kilograms or more, and harvesters slice away every leaf with a long-handled blade called a coa to reach them.

Which compound makes chilli peppers burn mammals yet goes unfelt by the birds that spread their seeds?

Capsaicin works as seed protection: mammals' molars would grind the seeds up, while birds swallow them whole and drop them somewhere new.

Digoxin, a medicine for heart failure, was first isolated from a species of which poisonous garden flower?

Foxglove remedies entered medicine in 1785, when William Withering published the first systematic account of using the plant against dropsy.

Northern Europeans first learned of tulips in the 1500s from diplomats posted to which empire's court?

Ottoman court society grew so fond of the flower that a peaceful stretch of the early 1700s is still called the Tulip era.

Which potent toxin is made in the seeds of the castor oil plant yet barely reaches the pressed oil?

Ricin does not dissolve in oil, so castor oil stays safe, while the leftover seed cake is too toxic to feed to cattle untreated.

Fig trees are pollinated by tiny females of which insect, which crawl inside the unripe fig to lay eggs?

Wasps pay for the nursery with their lives: the female lays her eggs inside the fig, pollinates its hidden flowers and then dies there.

Which carnivorous pond plant sucks water fleas through a trapdoor faster than the eye can follow?

Bladderwort traps sit under negative pressure, so the lightest touch on a trigger hair breaks the seal and the prey is swept in with the water.

Which plant family, home to Spanish moss, has the pineapple as its only commercially important food crop?

Bromeliads gave Europe a craze as well as a crop: Spanish conquistadors brought the pineapple home and it became a favourite motif in art and sculpture.

Which vegetable is not a root but a swollen stem that forms at the tips of long, thin stolons?

Potato tubers show their true nature in their 'eyes', which shelter the buds that new shoots grow from; a sweet potato, by contrast, is a genuine root.

Parsnips and radishes are swollen examples of which single thick structure that grows straight down?

Taproot is the name for one dominant, tapering root; many plants later replace theirs with a fibrous network, but these vegetables keep it as a food store.

The green heads of broccoli are picked as tight clusters of which plant part, before they turn yellow?

Flower buds left unpicked open into small yellow four-petalled blooms, so a head of broccoli is cut by hand as soon as it is fully formed.

Which sugar-rich liquid do flowers make to tempt visiting animals, and bees then turn into honey?

Nectar also buys protection: some plants make it outside their flowers to feed ants, which defend the plant from leaf-eaters in return.

Ginger and turmeric are spices cut from which kind of creeping underground stem?

Rhizome pieces can each grow into a whole new plant, which is how ginger is farmed: from planted chunks of the spice itself.

Which male organ of a flower is a slender stalk, the filament, topped by sacs that release pollen?

Stamen numbers vary wildly: a canna flower manages with half of one, while 3,482 have been counted in a saguaro cactus flower.

Which part of a pea flower swells into the pod once the flower has been fertilised?

Ovary walls ripen into the fruit while the ovules inside become seeds, which makes a pea pod a fruit and every pea in it a seed.

Which usually green outer parts of a flower shield it in bud and together form the calyx?

Sepals sometimes outlive their first job: on an aubergine the green calyx keeps growing along with the fruit instead of withering away.

The crunchy sticks of celery and the red stalks of rhubarb are both which part of a leaf?

Petiole is the botanical name for a leaf stalk, and cardoons, thistle-like relatives of the artichoke, are also grown as a crop for theirs.

Asparagus spears are picked as which part of the plant, before their buds open and they turn woody?

Young shoots differ by sex: male asparagus plants tend to send up smaller, thinner spears, and female plants larger, thicker ones.

Sweet peas and grapevines climb with which thread-like organs that coil around a support when touched?

Tendrils are choosy about what they grab: they coil at a touch, yet avoid twining around their own plant or neighbours of the same species.

Which ring of dividing cells, sitting between a tree's bark and its wood, makes the trunk grow thicker?

Cambium cells divide in both directions, adding new wood on their inner side and new bark tissue on their outer side.

Which sugar-carrying tissue forms a tree's inner bark, so stripping a ring of bark can kill the tree?

Phloem can even be eaten: in Finland it has been dried, milled into a flour called pettu and baked with rye into bark bread.

Which tiny outgrowths of single skin cells let a plant take up far more water and minerals from the soil?

Root hairs are so delicate that repotting a plant can pull many of them off, which is why a freshly transplanted plant may wilt.

The pale speckles on an apple or pear skin are which gas-exchange pores, also found in tree bark?

Lenticels on a European pear double as a ripeness gauge: the pale dots darken to brown as the fruit becomes ready to pick.

An onion is which kind of storage organ, built of fleshy scale leaves wrapped around a squashed stem?

Bulb scales are swollen leaves, and cutting them releases a compound that irritates the tear glands, which is why slicing an onion makes people cry.

Which first leaves of a seedling are already formed inside the seed before it sprouts?

Cotyledons are so basic to a plant's design that botanists split the flowering plants into monocots and dicots by whether a seedling has one or two.

The red 'petals' of a poinsettia are not petals at all but which kind of colourful modified leaf?

Bracts on a poinsettia only colour up after long nights: the plant needs at least fourteen hours of darkness a day for six to eight weeks.

What do botanists call the sharp points on a cactus, which are modified leaves rather than branches?

Spines are leaves in disguise, while true thorns are modified branches; besides deterring grazers, they shade the stem and help it lose less water.

Which darker inner wood of a tree trunk has changed chemically to resist decay better than the sapwood?

Heartwood is named only for its position, not its importance: a tree can thrive with its heart completely decayed.