Originating in the New World, peppers have been a universal culinary essential since Columbus’ voyages of exploration. Grown mainly for their edible fruit, they include both chillies (which are hot) and sweet peppers (which are not). Centuries of selection by both breeders and observant farmers have produced a diverse range of varieties that will keep even the most demanding gardeners occupied for years.
The exact number of pepper varieties in existence is impossible to determine. There are certainly thousands of them, with plant breeders and natural crossing guaranteeing a constant supply of new ones.
Despite these huge numbers, plant taxonomists have managed to arrange peppers into a workable classification system that makes them somewhat easier to understand and appreciate. They all belong to the genus Capsicum, which in turn is divided into more than 20 species, five of which have been domesticated. The five domesticated species are distinguished from each other by differences in their physical characteristics, including flower colour and arrangement on the stems:
• Capsicum annuum includes sweet peppers and most of the more common chillies, including the cayenne types found in shops and supermarkets. Conspicuously diverse, the C. annuums are probably the most popular of the domesticated species, both in the garden and the kitchen. The flowers are usually borne singly along the stem, and their petals are most often white, though they can sometimes be purple, or white with a purple fringe.
Group shot of Capsicum annuum peppers showing different shapes and sizes; a purple tinged C. annuum flower.
• Some of the most notorious peppers are varieties of C. chinense. Generically known as habaneros, they have a well-earned reputation as being extremely hot, and they include the hottest chillies ever measured, such as the Trinidad Scorpion, Dorset Naga and Bhut Jolokia. There are exceptions, however, and some, such as Apricot, have little or no heat at all. Regardless of their heat level, habaneros usually have an appealing fruity aroma that goes well with citrus-based salads and sorbets.
Group shot of Capsicum chinense chillies.
Habanero flowers are usually a whitish green, and are arranged in bunches of two or more along the stem. The fruit usually have an annular constriction located between the peduncle (the fruit stalk) and the calyx (the small, leafy structures between the peduncle and fruit). The plants tend to be slow growers, needing a long, hot season to produce fruit.
Capsicum chinense chillies are arranged in bunches; C. chinense or habanero chillies have an annular constriction at the base of the stem.
• Called locoto or rocoto in South America, C. pubescens is recognised by its hairy leaves and dark purple seeds and flowers. The fruit are hot, thick-fleshed and either round or pear-shaped.
Capsicum pubescens chillies have purple flowers and the fruit have black seeds.
• C. baccatum is known as aji throughout South America (though in Britain not all chilli called 'aji' are C. baccatum). Their flowers have distinctive brown or green spots on the petals. The fruit tend to be hot – though there are some exceptions to this – and their size and shape can vary considerably.
Group shot of C. baccatum chillies; the flowers of C. Baccatum have green spots on the petals.
• The last, but certainly not the least, of the domesticated species is C. frutescens. Developing from greenish flowers borne singly (or sometimes in pairs), the fruit tend to be hot and quite small. The species’ claim to fame lies with the Tabasco variety, the main ingredient in the famous hot sauce from Louisiana.
The colourful sight of tabasco chillies.
The majority of peppers varieties have stems and leaves that are coloured in the ubiquitous green of the plant kingdom. However, not all are created alike, and ornamental chillies – grown for looks as well as for heat – often have stems that are some shade of purple, ranging from a light touch-up to a dark coating of what looks like black paint. Like the stems the leaves can also display varying grades of purple, and in particularly showy varieties, they can be variegated white, green and purple. Fruit colour, too, is a variable trait that differs according to both variety and stage of ripeness.
Depending on the variety, unripe fruit are normally a shade of green ranging from light lime to blackish green, though there are some that are pale yellow, a hue of purple or a mix of the two. The colours change as the fruit ripen, turning either red, yellow, orange or, less commonly, brown. In extreme cases the colour changes can be quite dazzling. The chilli variety, NuMex Twilight is a perfect example; its fruit start out purple before turning yellow, then orange and finally red as they mature. As plants have fruit at all stages of ripeness plants can have all the colours simultaneously on each plant, making a spectacular show that wouldn’t be out of place in a floral bouquet.
Assortment of peppers showing the range of unripe colours (various shades – from lime green to almost black – of green, yellow and purple) and ripe colours (yellow, brown, red, orange, peach).
Chillies ripening from green to orange, yellow and red.
Physical traits such as shape, size, colour and flesh thickness define a fruit’s form, and they come together in myriad combinations that vary from one pepper to another. In defining fruit form the shape usually plays the major role, though the support given by the other traits is often indispensable. Using shape as a starting point, pepper fruit naturally fall into a number of prescribed categories, a few of which include the following:
• Jalapeño. The name is apparently derived from the Mexican town where this chilli originated. The thick-fleshed, elongated fruit are somewhat fat and sausage-shaped, usually coming to a blunt end. Their colour changes from green to red as they mature, though the immature fruit are sometimes a yellowish green. Heat levels are usually mild to warm.
• Cayenne. The long, thin fruit of cayenne peppers usually end in a sharp point. When immature, they are normally green, though some fruit start out as purple. As they mature, the colour changes to either red (the most common), orange or yellow. Their heat level ranges from sweet, i.e. no heat, to extremely hot. The flesh is thin, making the fruit ideal for drying.
• Ancho/poblano. Translated from the Spanish, ancho means ‘wide’, which may refer to this chilli’s broad shoulders. The thick-fleshed fruit are large and heart-shaped, though some varieties produce fruit that are more elongated than others. Heat levels are rather low, and the colour changes from a characteristic blackish green to either red or brown.
• Bell. ‘Bell’ is a bit of a misnomer since ‘blocky’ better describes the fruit shape of this pepper. Usually large, thick-fleshed and sweet, they are the best known types in the shops and supermarkets. The young fruit are normally some shade of green, but there are some varieties that are purple, e.g. Tequila, or almost white; while those of the mature fruit are red, yellow, orange or brown. Not all bell peppers are large, however, and some varieties produce fruit that are quite small. Likewise, not all varieties are sweet, and hot ones have been around for years. Nor are they always thick-fleshed. A bell pepper that breaks all the rules is the variety Pettie Belle – it is a small-fruited, hot habanero with thin flesh.
Different shapes of pepper fruit: jalapeño, bell, poblano and cayenne.
The ability of pepper fruit to take on the shape of another object is called morpho-mimicry. It is a common phenomenon, and the other object that the fruit mimics is often integrated into the pepper’s name. Granted, the imagination is sometimes overworked, but for the most part the name fits the fruit’s shape:
• Head apparel e.g. Scotch Bonnet and Friar’s Hat
• Body parts, e.g. Corno di Toro (bull’s horn), Chicken Heart, Peter Pepper, Rooster Spur, and Bird’s Beak
• Fruit and vegetables, e.g. tomato, pumpkin, squash, cherry and mushroom.
Morpho-mimicry in peppers: Friar's hat, Rooster Spur and a tomato pepper.
Plant growth habit
Peppers are renown for their diversity, and this diversity manifests itself even when it comes to the shape and height of the plants. There are plenty of varieties to choose from, beginning with those that are naturally short. They include the likes of Stumpy (upright and compact) and Prairie Fire (gently spreading), which are ideal for the narrow confines of a windowsill. Then there are the taller ones, such as Joe's Long Cayenne and Joe E. Parker, that look like shrubs and are perfect for smaller greenhouses and tunnels where height is a problem. Moving up the scale are the varieties that grow tall and gangly, like Pimiento de Padron and the ancho/poblano types: these are best suited to larger, more spacious structures. Pepper plants are plastic, and the treatment they receive as they grow can, to some extent, influence their natural habit of growth. The extreme is Dorset Naga, which when allowed to grow completely unrestricted can reach over 2 metres high.
Growing chillies in pots rather than in the ground, for example, confines the roots, which in turn can reduce plant size. Pot size, too, affects plant size, and the smaller the pot, the smaller the plant. The control of growth habit can be taken even further by pinching out the growing tips of the main stems, forcing the formation of bushier plants that some gardeners may find attractive.
Two extremes in growth habit: Stumpy is a very compact chilli variety and does very well on a small windowsill; given unrestricted root space Dorset Naga can grow in excess of 2 metres.
Two plants of the same variety, sown at the same time. The plant on the left has been allowed to grow unrestricted, it has flowers and young fruit on it. The plant on the right had its growing shoot pinched out; it is bushier, but has no flowers yet and will produce chillies much later.
For some unfathomable reason, chillies have assumed an almost mythical status in the vegetable garden. Maybe it is because of their heat, or possibly due to the extraordinary selection of a diverse range of varieties. Whatever the explanation, they stand apart in most gardeners’ minds and so deserve special attention.
The heat in chillies is caused by a group of chemicals called capcaicinoids. These chemicals are found only in the fruit, and the more concentrated they are, the hotter the chilli is. Their concentration is affected mostly by the choice of variety, though levels are also influenced by growing conditions and age of the fruit.
The degree of heat is expressed in Scoville Heat Units (SHU), named after Wilbur Scoville, an American pharmacologist who devised a taste test for measuring chilli heat in 1912. The scale starts at zero for sweet peppers, which have no heat, and increases up to the current record holders – varieties of C. chinense from Bangladesh, Northeast India and the Caribbean – which reach heat levels of 1,000,000 SHU or more.
Chillies are a versatile cooking ingredient, and the physical features of their fruit – particularly size, shape and flesh thickness – determine how they are best used in the kitchen. On the basis of these features, varieties can be broadly divided into two culinary types, though once in the kitchen, the distinction is often blurred:
• Spice-type chillies have relatively small, thin-fleshed fruit valued mainly for their heat. Essential in Thai, Indian and Caribbean cooking, they include cayenne and Scotch Bonnet chillies and are normally added to dishes in such small quantities that, except for their heat, they usually go unnoticed. Because of their thin flesh, they are easily dried and made into flakes or powder.
• Vegetable-type chillies have larger fruit with thicker flesh. They bring both heat and substance to a dish, and can be used in much the same way as sweet peppers. Their heat levels range from mild (as in New Mexican/Anaheim and ancho/poblano types) to hot (for example, Rocoto types). Despite their thick flesh, some types, such as the anchos/poblanos and jalapenos, are dried and then either powdered, diced or used whole.
Joe's Long Cayenne is a spice chilli.
... and finally
Growing peppers is like stamp collecting and train spotting: an obsessive activity that is difficult to control. One stimulus for this obsession is the numerous varieties available to the gardener, and no matter how many are grown, there’s always one more to try.