WHAT, EXACTLY, ARE HERBS?

It’s a frequently asked question. It would be wonderful to have a simple and straightforward answer but, unfortunately, no such answer exists. Part of the problem is that the word ‘herb’ means different things to different people.

‘Spice’ means nothing at all to botanists, and when they think of herbs they mean non-woody vascular plants that die, or at least waste away, after flowering. Most cooks, and many gardeners, would find that definition essentially useless. For one thing, they’ve noticed that some ‘herbs’ can with age become woody – which means the stems are tough enough to survive frost without melting away as annuals do, and are similar to the twigs of a tree – and don’t actually ‘waste away’ (for example: rosemary, sage and thyme).

Cooks often distinguish herbs from spices by the part of the plant used in cooking: ‘herbs’ are foliage or flowers, while ‘spices’ consist of bark, seeds and roots. In practice, at least in the European tradition, ‘herbs’ are parts of plants that are grown in domestic gardens, while spices are almost always imported – usually from tropical parts of the globe. Unfortunately, no matter which set of rules one chooses, it is bound to have so many exceptions that its usefulness is questionable.

For example, mustard (Brassica and Sinapis spp.) and coriander (Coriandrum sativum) seeds are treated like spices but they thrive in temperate gardens, and both produce foliage that is used more like the ingredients we call ‘herbs’. Young mustard leaves are eaten as a salad herb, while older leaves are cooked slowly, as pot-herbs. Coriander leaves, cilantro, are used sparingly as a fresh herb in many cuisines (indeed, in Thai kitchens the leaves, stems and roots are considered to be different ingredients, and have distinct names). In some places, like Vietnam, coriander is used by the handful – it’s practically a vegetable.

We also use several different terms to categorize the plants, and parts thereof, we use in our kitchens. We have already seen salad herbs and pot-herbs, but there are also herbal teas (infusions that are better described as tisanes). Some of these plants and plant parts serve primarily as ‘seasoning’, while others do not. This is not a problem for English speakers only. In Germany, ‘kraut’ refers to any ingredient based on leafy plant matter; ‘sauerkraut’ is probably familiar to everyone, but ‘bohnenkraut’ may not be – the word means ‘bean herb’ and it’s used for both summer and winter savory (Satureja spp.). Chinese cooks are heavily dependent upon a number of fermented ingredients to add flavour to their dishes, but use only a couple of spices, and perhaps three herbs, as seasoning. However, their cooking features a large variety of leafy greens we would consider to be pot-herbs. The Vietnamese, as noted above, use leafy plants we would describe as ‘culinary herbs’ in such large quantities that they seem like salad greens – rather intensely flavoured, to be sure, but ‘salad’ nonetheless.

Virtually every reference describes cloves as a ‘spice’, yet they are the unopened buds of flowers – which, by conventional logic, suggests that they should be listed among the herbs. While Europeans only know the dried flower buds of this tropical evergreen tree, an Indonesian might use its leaves, twigs and bark. The clove tree provides seasoning, food, perfume and even cigarettes called kretek, all made with one or more parts of the tree. The Eurocentric term ‘spice’ seems wholly inadequate when seen from the perspective of the Indonesians who harvest it.

What we choose to call ‘herbs’ and ‘spices’ are often little more than accidents of geography, history and contemporary modes of transportation. Many of the ingredients we call ‘herbs’ are parts of plants which traditionally have been grown in European gardens. Before the Age of Exploration ‘spices’ could only be obtained through a series of intermediaries who, for commercial reasons, preferred to keep the knowledge of their sources proprietary. These sources were so mysterious to European consumers that many believed that they grew only in the Garden of Eden. Since cinnamon, cloves, ginger and pepper could not be grown in Europe’s temperate climate, they were imported from distant lands, on the backs of camels that trudged along secret spice routes, or, later, on very small ships. The spices changed hands many times along the way (the price rising at every step, an early example of what we would describe as ‘value added’ today). The costs imposed by the spice traders and the dangers they faced along the way forced them to choose only the most densely flavoured parts of tropical plants. Handling large amounts of leaves and twigs was simply not cost-effective.

If the discussion of herbs and spices has told us anything, it is that distinguishing between them is troublesome. While most of us are certain that cinnamon is a spice (it is the inner bark of a tropical tree, and its flavour and aroma are intense), the ancient Greeks and Romans had a different take altogether. They imported vast quantities of leaves they called phyllon and malabathrum, which came from a tree that is closely related to the one that gives us cinnamon (malabathrum is Cinnamomum tamala, while true cinnamon is C. zeylanicum). These leaves have an even stronger cinnamon quality than the bark, so perhaps we should be asking ourselves why the use of these leaves died out. One answer is that it didn’t – it’s still commonly used in the cooking of South Asia (Bhutan, India and Nepal).

Simply put, herbs are all those plant parts – other than spices (given the caveat that the definition of ‘spices’ is less than clear) – that we use to enhance our food. Traditionally, Europeans and emigrants from Europe have used the term ‘herbs’ for those plant products – used to add flavour and scent to their dishes – they could grow for themselves. ‘Spices’ were used the same way, but were always imported, and hence more expensive. This led to the perception that spices were somehow more prestigious than herbs – which, in turn, led to the use of spices in court, or haute, cuisine. Herbs tended to be seen as common everyday ingredients, more suitable for ordinary meals.

This difference of approach is arbitrary, based on class distinction, and has nothing to do with the ingredients themselves. In today’s world, the expense of shipping ingredients from distant shores has been reduced to the point where economic considerations are irrelevant. While clarifying the precise divisions between herbs and spices may be difficult, what is certain is that we value all of these plant parts because they contain small but intense quantities of alcohols, aldehydes, acids, alkaloids, essential oils, esters, ethers, terpenoids and so on, which add flavour and aroma to our foods. In today’s kitchens, the only real difference between herbs and spices is the concentration of the flavouring compounds they contain. Spices are invariably stronger, and tend to be added to dishes earlier to extract as much flavour as possible. Herbs, especially fresh herbs, tend to be added later in cooking, so that volatile flavours and aromas are not lost before serving.

While we’re discussing the chemicals that give herbs their distinctive tastes and aromas we should correct a popular misconception – one that has been repeated in countless recipe books. We are often told that, in substituting dried herbs for fresh, we should reduce the amount used to one-third of the original recommendation. That may be true for some herbs, but as a guiding principle it has some serious drawbacks. When herbs dry, they tend to lose some of their volatile compounds. If they lost them in any sort of consistent manner, there might be some use to the general rule of substitution. However, not all herbs are so dependable. Some herbs become stronger when dried, some do not. Some compounds are altered into different compounds as they dry (due to fermentation or other chemical processes). Again, some essential compounds are more volatile than others. These variables can produce a stronger-flavoured herb, a weaker one or a totally different one.

For example, fresh tarragon has a lovely anise-like scent due to the presence of anisol. Unfortunately, when the leaves lose their water, they also lose much of their anisol – so their hint of liquorice is greatly diminished. At the same time, a bit of fermentation causes other compounds in the leaves to convert to coumarin, which gives dried tarragon the pleasant – but different – scent of new-mown hay.

When substituting dried herbs for fresh, we must consider not only the amount to be used, but also the fact that the substitute is actually a different ingredient from that which was originally specified.

Our ancestors may not have known about the chemical compounds that gave herbs their appeal, but that didn’t stop them from believing that these plants had medical or magical properties. The Doctrine of Signatures was an ancient notion, now regarded as a superstition, that led people to believe that the appearance of herbs was somehow connected to their medical properties: for example, the leaves of hepaticas resembled the liver, so were thought to be beneficial to that organ. Some herbs actually do have medical properties, but that’s beyond the scope of this book. For us, the magic that they add to our tables is more than enough reason to study them, their origins and their spread around the globe.

One final issue must be addressed. While we put aside our confusion about what are, or are not, herbs, the names we have given these plants is another story. Common names for plants (and birds, fish, animals and so on) are notoriously troublesome. Many completely different species often share the same or similar common names. This is not surprising, since different plants may serve the same culinary function and be treated as if they were the same species. Sometimes a new plant, in a new place, simply reminded someone of a familiar plant in the old country. To try to minimize such confusions, botanists prefer to use the Latin binomial system invented by Linnaeus. It may seem pedantic and overly fussy, but it’s the best method we have to be clear about the plants we’re discussing. Unfortunately, even the binomial system has its weaknesses.

Science is an ever-changing field. As scientists learn more about the connections – and differences – among species, taxonomists (the people responsible for the naming and categorizing of species) sometimes have to change the scientific names given to plants. Since Linnaeus began the process of systemizing the entire living world, back in the eighteenth century, a lot of science has changed. Consequently, many of the useful terms we used to use to categorize plants have been changed, eliminated, subdivided or recombined with others and, as a result – especially if one consults older texts (such as herbals) – the exact identity of the plants that interest us is occasionally uncertain.

A rational person might suspect that for a system of taxonomy to be successful, universality is a key requirement. Such a person is bound to be disappointed. Successive generations of scientists have often chosen to change the system, sometimes for very good reasons – but not everyone adopts the changes. Different authors, in different places, have elected to incorporate some, all or none of the changes made by others. As a result, a single species might have several different scientific names. It might be listed in several different genera. It might even appear in more than one family. All we can do is try to use the most recent names available, acknowledge the changes when we can and understand that our best efforts will probably go awry within a generation or less.

Written by Gary Allen in "Herbs -A Global History", Reaktion Books, London, UK, 2012. Digitized, adapted and illustrated to be posted by Leopoldo Costa.