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The Royal Botanic Gardens guide to the world’s top ten spices

Take a journey across the seas and spice routes with the world’s top ten spices from The Royal Botanical Gardens at Kew

Spices sit in our cupboards and on most people’s dinner tables. We have become accustomed to tasting them in our food and using them in our cooking, but how often do we stop to think about where they come from and how they’re grown? Here are the ten most important spices in the world.

Black Pepper – Piper nigrum

a botanical illustration of a pepper plant with lush green leaves and pepper corns

The pepper plant (Piper nigrum, L.) is a native of S. India. White and black pepper are from the same plant. Whole black pepper is the ripe fruit untouched, and white pepper is the same thing with the outer skin of the fruit removed. © Board of Trustees RBG Kew

We have been using pepper for thousands of years. But like many spices, its true origins were a well-kept secret until a few hundred years ago.

Along with a lot of spices it came to the west along the Spice Route – Arab traders controlled the supply and wanted to keep the secret of where the plants were grown. It passed through lots of hands on the way, so by the time it came to the west it was very expensive and considered a luxury.

It comes from India and has a long history of being used both as a flavouring and for medicinal purposes. Even today it’s used in traditional Chinese medicine and other medical systems.

The Portuguese were at the forefront of the exploration to find pepper and many other spices during the early 1500s and at one point it was so significant that it was at the heart of global politics and exploration.

It’s an unassuming-looking plant but it’s been behind some of the major cultural shifts in history and helped us discover the world around us; countries have been built on the power of pepper.

Capers – Capparis spinosa

a botanical illustrations showing the caper plant

© Board of Trustees RBG Kew

Every time you pop a caper into your mouth you’re eating the closed flower bud of a plant. They are usually hand-picked early in the morning, before the flowers open.

Some are still picked from the wild, but they are also cultivated – although the process of modern agriculture has made them susceptible to pests or disease. The wild ones are more resilient, so for us at Kew it’s important we can go back to that genetic source and make sure we have supplies for the future.

Our Millennium Seed Bank holds a lot of spices to make sure that whatever happens in the future we don’t lose some of these useful plants. We’re finding out more about them every day so it’s important to look after that genetic diversity.

People have been eating capers in certain parts of the world for thousands of years. Archaeological discoveries show capers being used in Syria as long as 10,000 years ago. They’ve been used in the Middle East and Mediterranean since ancient times.

The Romans used capers a bit like we might use salt and pepper today. They would be dried and ground and sit on every table. The way we use spices today can be different to how they were used in the past.

Chillies – Capsicum annuum

a botanical illustration of a chilli pepper

© Board of Trustees RBG Kew

There are thousands of different varieties of chillies but most come from the same species: Capsicum annuum, which has been bred by humans into lots of different varieties.

Mild bell peppers are the same species as blow-your-head-off Carolina Reaper chillies. It’s the same plant but because of human intervention we have managed to produce all of these different varieties that suit our tastes.

It’s also one of the few spices that come from the Americas. They are easy to grow, and in the wild are distributed by birds who don’t respond to the heat, which means they can get to the seeds. So they are now grown all over the world.

Chillies have been used for thousands of years; the Aztecs would burn them and, like pepper spray, the smoke would sting the eyes of their enemies and help keep them at bay.

This irritant effect also has medicinal properties that is used in some pain relief treatments. We’re still learning how to harness the power of plants for medicinal purposes.

Plants produce a huge range of chemicals and understanding how the plant uses these chemicals – often as defence mechanisms – can also help unlock beneficial ways to use them ourselves.

Cinammon – Cinnamomum verum

a botanical illustration of a plant with flat long leaves

Laurus cassia (Persea cassia, Cinnamomum cassia), cinnamon. Joseph Jacob Plenck , Icones Plantarum Medicinal, Vol. 4, 1791. © Board of Trustees RBG Kew

Its origins were cloaked in mystery and all kinds of tall tales were spread to keep people from finding out the truth about cinammon, such as it being grown on top of a mountain guarded by ferocious birds who made nests out of the cinnamon sticks.

The only way to get to it was by tempting the birds with hunks of rotting meat which they would take back to their nest. The nest of cinnamon would collapse under the weight and the sticks would fall to the ground allowing the intrepid traders to grab them before they were attacked. Of course, people eventually found out where it really grew – in Indonesia and Sri Lanka.

Actually, most of what we buy today thinking it’s cinnamon is really a different but related plant called cassia. It looks and tastes similar – if a bit harsher – but is much cheaper than true cinnamon.

At Kew, we help verify plant material being sold is actually what it claims to be, especially if it’s being sold for medicinal use. If you buy cassia thinking it is cinnamon your mulled cider might not taste quite as spicy, but it won’t do you any harm. Other plant imposters are not quite so harmless (see Star Anise).

Juniper – Juniperus communis

a photo of a juniper bush with berries on it

Photo taken at the National Trust’s Plant Conservation Centre in Taunton, Devon. Photo Copyright Wolfgang Stuppy & RBG Kew.

What’s not to love about juniper? You need juniper to produce gin – it’s one of the main flavourings. It’s also the only conifer we get a spice from and one of only three conifers native to Britain.

Juniper ‘berries’ are actually little cones. Although it’s grown quite widely around the world, in Britain it’s under threat – there are conservation plans in place to replant and protect it.

As well as coming under threat from habitat loss, fungal disease and grazing by animals, juniper bushes are slow-growing, so Kew is working to collect juniper seeds for safekeeping in our Millennium Seed Bank as well as being involved in reintroducing juniper seedlings into the wild to make sure this native species doesn’t die out.

Gin making originated in the Netherlands, when much of the juniper used was exported from Scotland, where it still grows today. The word gin actually comes from ‘jenever’ which is the Dutch name for juniper.

Now most juniper for our gin comes from the Balkans and Italy, though there is some still harvested in Scotland but it’s usually for bespoke luxury gin labels.

Next time you enjoy a gin and tonic, spare a thought for the special conifer that’s helped to create it.

Nutmeg and Mace – Myristica fragrans

a botanical illustration showing the nutmeg plant and its braod flat leaves together with the nutmeg kernel

Nutmeg. © Board of Trustees RBG Kew

This is an interesting plant for lots of reasons but it’s unique in that we get two spices from the same plant.

Nutmeg isn’t actually a nut. It’s a seed, while mace is the lacy structure covering the seed. They are two completely separate spices.

Historically used for a long time for medicine, food, perfume, preservation and embalming, nutmeg is still used today in things like cough syrups and toothpaste, which have nutmeg oil in them.

It originated from the Banda Islands in Indonesia, and fuelled much exploration to find it and sadly a lot of death and destruction too. The Portuguese were the first Europeans to find and control the source of nutmeg but lost control to the Dutch. Meanwhile the British found it growing on Run, one of the smaller islands in the Bandas, and took control of that.

Dutch New York – or New Amsterdam as it was then called – was offered to the British in exchange for the control of Run and all the nutmeg that was on it. The deal was done and New Amsterdam became New York – all because of an unassuming seed.

In recent years Grenada was the main nutmeg producer, the income from which sustained the island’s economy, until 2004, when Hurricane Ivan wiped out 90% of the nutmeg trees. The basis of their GDP went overnight and they are still recovering from it now.

One unassuming seed still has the power to affect nations. Which leads us to an interesting question. What are spices worth to you? You may know the price but what about their value?

Spices are such an integral part of our everyday lives it’s easy to take them for granted but for many people, even countries, their value is as high today as it was when New York went by another name.

Saffron – Crocus sativus

a botanical illustration of the nutmeg plant

Crocus sativus officinalis, saffron. REGNAULT Nicolas François (1746-c.1810) and Genevive de Nangis REGNAULT (b.1746). La Botanique mise a la portée de tout le Monde: ou collection des Plantes d’usage dans la Médecine, dans les Alimens et dans les Arts.Vol. 2, 1774. 80. © Board of Trustees RBG Kew

A beautiful flower, saffron is a member of the crocus family. It’s been cultivated by humans for such a long time it doesn’t occur naturally in the wild anymore and as a consequence there is very little genetic diversity in this particular species.

Most saffron comes from Iran (95%) and, like capers, the flowers have to be harvested early in the morning before they open because the saffron is actually the stigma – the female reproductive parts of the plant. There are three stigma that sit inside every flower and it’s those stigma that are the beautiful bright orange saffron threads that we see.

It’s very labour intensive, and consequently it is really expensive. You have to pick something like 200 flowers just to get a gram of saffron. It’s usually collected in huge baskets, often by families, who take the flowers back to the homestead and then spend the rest of the day picking out the stigmas.

The harvest only occurs for a few weeks in a year but that can provide enough income for a family to last the rest of the year.

We used to grow a lot of it in the UK – Saffron Walden got its name because it was a centre of saffron production during medieval and Tudor times. It’s beginning to come back, with saffron farms reappearing outside Saffron Walden and Norfolk. But it also offers potential for different uses.

Historically it was used to alleviate depression and quicken the mind, and recent scientific research shows it could help with memory loss and may help treat some symptoms of dementia and Alzheimer’s. Kew scientists are involved in looking at that.

Star Anise – Illicium verum

a botanical drawing of a plant with large drooping leaves

Star anise © Board of Trustees RBG Kew

Used medicinally for thousands of years, star anise contains the material basis for anti-flu drugs such as Tamiflu and some anti-cancer treatments. It looks very similar to Japanese anise and it’s not until you look on a molecular level that you can tell which is which.

Unfortunately Japanese anise is toxic so, as with all things, it’s important to buy properly labelled products so you know what you’re buying is genuine. Kew scientists developed a special method of distinguishing between the two species and works with regulatory authorities and manufacturers to ensure the correct one is being used.

Most star anise is grown in one particular region of China which is where it originates, so in terms of supply it’s quite vulnerable to unexpected environmental changes. A very bad winter in the region a few years ago affected the harvest and had an impact on the global supply.

Apart from its medical properties, it’s used as flavouring in Sambuca and Ouzo, and it’s used in mouthwashes – so even if you don’t know what a spice looks like, the chances are you are using a product it contains.

Turmeric – Curcuma longa

a botanical illustration of a spindly plant with luscious central flower

Turmeric © Board of Trustees RBG Kew

A member of the ginger family – all of the interesting stuff with turmeric goes on underground and the spice actually comes from an underground stem called a rhizome. Probably grown originally for use as a dye, it is native to south-west India and revered as a sacred plant in many cultures.

Widely used in cooking, it also has historic use medicinally; modern scientific research is beginning to unlock some of the plant’s medicinal properties and it may have potential in treating some forms of cancer.

Often hand-cultivated and hand-picked, it’s another spice that is labour intensive to produce. It’s also used as a colourant in many foods we eat. Look out for E100 on packaging – that’s curcumin, a naturally occurring chemical compound found in turmeric.

Vanilla – Vanilla planifolia

a botanical illustration of an orchid like flower with yellow stamens and green pods

Vanilla © Board of Trustees RBG Kew

One of the most popular flavourings found in so many different foods, vanilla pods are really difficult to produce. Every single flower has to be pollinated by hand in order to produce the flower which in turn produces the pod.

Once you’ve got the pod they have to be picked at exactly the right time. They then go through a long process of drying, curing and sweating before you get that wonderful vanilla aroma and flavour, which is made of 200 different chemical compounds.

All of that takes a lot of time and a lot of effort so it’s the most expensive spice after saffron.

It originated in Mexico, where it is pollinated by bees and, some people think, potentially by hummingbirds as well – although the jury is still out on that. As part of the global trade vanilla plants were taken to other parts of the world like Madagascar and Reunion Island, but when they eventually got them to flower they didn’t produce pods and they realised it was because they hadn’t taken the natural pollinators with them.

They tried to bring the bees over from Mexico but they didn’t make the journey and eventually they found a way of hand-pollinating successfully. Allegedly it was a 12-year-old boy from Reunion Island – unfortunately a member of the slave population – who found this way of hand pollinating them and that allowed the vanilla industry to spread to different parts of the world. Now most of the vanilla we use comes from Madagascar.

It’s an orchid, one of the most diverse plant families in the world, and evolved around 65 million years ago bringing a whole new meaning to ‘old spice’! There are several species of vanilla but the vast majority of the vanilla we use comes from Vanilla planifolia.

Visitors can meet Kew scientists and hear about some of the behind the scenes work they do every Tuesday and Thursday. See www.kew.org/kew-gardens/whats-on

All the botanical illustrations have been used with permission and come from Kew’s Library of Art and Archives. Some of them can be seen in the Marianne North Gallery at Kew. The photograph is of a plant in-situ at Kew.


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