Wednesday 21 February 2018

Beetroot: Contents


Beetroot (2004)

Stephen Nottingham




Contents
1. Introduction
2. History
3. Classification and Botany
4. Cultivation
5. Colour
6. Health and Nutrition
7. Cuisine
8. A Dictionary of Cultivated Varieties






© Copyright Stephen Nottingham, 2004

sf.nottingham@btinternet.com



"Stephen Nottingham's meticulously researched online book, Beetroot"
The Times (London), 15th August 2005



Please note: The information contained in this book is not intended to be used as a basis for self-diagnosis or treatment. It is recommended that a doctor is consulted if in doubt about treatment for medical conditions.


August 2004 SFN. 1

Beetroot: 1. Introduction


Beetroot (2004)

Stephen Nottingham

© Copyright: Stephen Nottingham 2004


1. Introduction

This book is about an extraordinarily useful plant called Beta vulgaris. In particular, it concerns one of this plant's cultivated forms: beetroot (beet, table or garden beet). The other cultivated forms of Beta vulgaris are leaf beets (spinach beet and Swiss chard), fodder beet, and sugar beet.
Wild sea beet is the ancestor of all cultivated beets. It grows in coastal areas in Europe, North Africa and Asia. The leaves of sea beet have probably been consumed since prehistoric times in Europe. Beta vulgaris was first domesticated for its leaves and leaf stems (petioles). Cultivated leaf beets were eaten throughout ancient times. The Greeks described colourful chards, a special type of leaf beet with elongated, broad and fleshy leaf midribs and petioles. In Roman times, chard was called beta.
The Romans were the first to take an interest in the root of Beta vulgaris, which they utilized for their medicinal properties. It was not until the sixteenth century that beetroot became known as a root vegetable. A wide range of beetroot cultivars were bred from that time onwards. The cultivation of beet for sugar production started at the beginning of the nineteenth century. Today, around half the world’s sugar is obtained from sugar beet. Chapter Two is about beets in time, tracing the history of cultivated Beta vulgaris from ancient times to the present day.
The classification of Beta vulgaris is the subject of Chapter Three. Within the taxonomic system of binomial nomenclature, established by Linnaeus, cultivated beets are currently considered to be within the subspecies Beta vulgaris subsp. vulgaris, while ancestral sea beet is considered as Beta vulgaris subsp. maritima. The different cultivated forms of beet are considered as distinct varieties. A complementary horticultural scheme, however, is usually applied for within-species (infraspecific) classification of beets. This scheme uses the concepts of cultivar and cultivar group.
The botany of Beta vulgaris is also considered in Chapter Three. Beetroot is a biennial plant grown as an annual for its storage root. Disparities between commonly used and botanical terms are clarified. Beetroot seed, for instance, is technically a fruit containing several true seeds.
The cultivation of Beta vulgaris is described in Chapter Four, with an emphasis on beetroot in gardens and allotments. From sowing seed to harvest and storage, each stage of cultivation is considered. Problems due to bolting (going to seed) and from pests and diseases are described, while ideal growing conditions are discussed. The chapter concludes with a look at biotechnology, considering genetically-modified sugar beet and how beet cultivation may be further modified in the future.
The characteristic colour of beetroot is investigated in Chapter Five. The pigments in beetroot, the betalains, are restricted in distribution. Therefore, beetroot has a distinct value as a dye source and for the health benefits arising from compounds related to these pigments. Beetroot red or betanin is extracted from beet roots on an industrial scale for use in food products (E162 in Europe), while beetroot colouring has been used as a dye since the sixteenth century. Betalains are usually taken up efficiently and processed in the human body. However, some people excrete red-coloured urine after eating beetroot, due to an inability to breakdown betanin - a condition called beeturia.
The composition of Beta vulgaris, with respect to its health and nutritional value, forms the basis of Chapter Six. Beta vulgaris has been considered a medicinal plant since ancient times, while the seventeenth-century herbalists ascribed many beneficial effects to its leaves and roots. Scientific research is confirming some of the benefits derived from beetroot, although other claims for it have to be regarded as 'old wives tales'. Beetroot juice has been advocated as a stimulant for the immune system and as a cancer preventative.
Chapter Six concludes on a lighter note with a section on beetroot and sex. Although long associated with rude good health, from its depiction in Pompeii’s brothels to Montgomery exhorting his troops to “find favours in the beetroot fields", do beetroot’s aphrodisiac properties really stand up?
The myriad uses of Beta vulgaris in the kitchen are related in Chapter Seven. Descriptions of dishes are given in an historical and cultural context. The first section looks at cooking with beet leaves and chard. Spinach beet (perpetual spinach) can be cooked like spinach, for instance, while Swiss chard is good steamed and covered in sauce.
Beetroot has been a staple winter root vegetable in Central and Eastern Europe for centuries. Many of the classic beetroot dishes originated in this region, including the most famous beetroot soup called borsch. Ukrainian borsch is described in this chapter, along with the side dishes that traditionally accompany it. The production of smaller globe-shaped beetroot varieties in North America and Western Europe led to beetroot’s increasing importance as a summer salad crop.
The different ways that beetroot are used in salads, as a hot vegetable to accompany meat and fish, and in pies, risottos and gratins are described here, in addition to methods for their preservation such as pickling. Beetroot juice is common in health drinks and it makes a good wine. Beetroot has enjoyed a revival in recent years in Europe and items on fashionable restaurant menus are noted throughout this chapter. A new generation of chefs has revived and updated traditional recipes, and in the process found new ways of using beetroot.
Beetroot is one of the most commonly grown crops in gardens and allotments, and there are numerous cultivars to choose from. Chapter Eight takes the form of a dictionary of cultivated varieties. It lists all the cultivars encountered in popular seed catalogues, and a range of heritage varieties obtainable from specialist suppliers. For each cultivar, information on history, size and shape, colour, resistance to bolting and disease, eating properties, and other characteristics are given. Additional information will continually be added, including photos and tasting notes based on my experience of growing and cooking a wide range of beetroot cultivars from my allotment in Stevenage, England.


© Copyright Stephen Nottingham, 2004

sf.nottingham@btinternet.com






August 2004 SFN.
1

Beetroot: 2. History


Beetroot (2004)

Stephen Nottingham

© Copyright: Stephen Nottingham 2004


2. History 
Wild sea beet (Beta vulgaris subspecies maritima) has thrived around the coastlines of Europe, North Africa, the Middle East, and parts of Asia, since prehistoric times. The leaves of sea beet have probably been collected and used as a potherb since humans first started experimenting with edible green plants. Sea beet was first domesticated in the eastern Mediterranean and the Middle East. It is the ancestor of all the cultivated forms of beet (Beta vulgaris subspecies vulgaris). This chapter traces the history of beets from ancient times to the present day.
Beta vulgaris was initially valued for its leaves and for the fleshy elongated leaf midribs that characterize chard. Leaf beets, including chard, have been popular food plants in Europe, North Africa and the Middle East since the start of recorded history. Beet (silga) was mentioned in an Assyrian text as growing in the Hanging Gardens of Babylon, one of the wonders of the ancient world, in around 800 BC. It was also referred to variously as selg, silq, silig, seig or salk in Middle Eastern areas from ancient times. The ancient Greeks and the Romans cultivated leaf beets for use as a potherb.
The Greeks presented beet as one of their offerings to the sun god Apollo in the temple at Delphi. The earliest Greek name for beet was teutlon or teutlion, probably because its foliage was thought to resemble squid tentacles. The plant is mentioned in two comedies (The Acharneans and Peace) by Aristophanes (around 444-385 BC), which were performed in Athens in about 420 BC. Aristotle (384-322 BC), the first philosopher to attempt to classify the natural world, described a red-coloured beet. His pupils Theophrastus (370-288 BC) and Eudemus (350-290 BC) also left accounts of beet. Theophrastus described a white or light-green kind called Sicula (after Sicily where it was first grown) and a black or dark-green kind. Sicula or cicla has been used as a taxonomic term for leaf beets (as opposed to beet roots) up to the present day. Theophrastus described beet as being a garden plant with many uses. The Greek physician Dioscorides also records two types of beet in the first century AD. Eudemus was not so farsighted in identifying future leaf and root beets, however, and he distinguishes four kinds: white, sessile, common, and dark or swarthy. Roman and Arab writers noted a variety of different colours in leaf beets, including pink and yellow coloured forms. The old varieties of chard available today are identifiable in the descriptions of colourful leaves and stems handed down in ancient texts. The Greeks ate the leaves of Beta vulgaris and utilized them, and occasionally the roots, medicinally.
The Romans consumed leaf beets in the same way as the Greeks, but they called the plant beta. Many Roman writers mention betas, including Apicius, Cato, Cicero, Columella, Dioscorides, Galen, Palladius and Pliny the Elder. The two main types of Beta vulgaris known to the Romans were white and black, which correspond with the two types described by Theophrastus. However, Roman descriptions of beet put more emphasis on the roots than did Greek texts. The Romans were the first people to become interested in the root of Beta vulgaris both as a medicine and as a food. Roman black beet represents beetroot in an early stage of development. Different types of Beta vulgaris would have hybridized freely in Roman gardens, with the seed from plants producing swollen roots being preferentially selected for future planting. The Romans were therefore the first people to cultivate beetroot.
The Romans were primarily interested in the roots of Beta vulgaris as a medicine. By the third century AD, the first recipes for preparing the roots of Beta vulgaris appear. The roots of both white beet and black beet were used medicinally. Roman recipes for beetroot were mainly for curative broth, to treat fevers and other ailments, but some were aimed at the epicureans of the day.
Recipes for both medicinal broth and adventurous culinary dishes have been handed down in Apicius' The Art of Cooking. The Roman gourmet Marcus Gavius Apicius lived in Tiberius in the first century AD. However, the book that bears his name dates from the late forth or early fifth centuries AD, because it was compiled by another author, who confusingly also wrote under the name Apicius. He combined two original texts by Apicius, on general recipes and on sauces, with a book on agriculture and domestic science by Apuleius (second century AD) and material from other sources. Apicius’s cookbook was edited and translated in 1958 by Flowers and Rosenbaum, under the title The Roman Cookery Book.
In the third part of The Art of Cooking, which is thought to have derived from Apuleius, there are five different recipes for broth to be used as a laxative. Three of these include beetroot. In one of these broth recipes, cleaned black beet roots (negro betacios) are either cooked in mulsum (a honey and wine mixture) with a little salt and oil, or boiled in water and oil with salt. The broth is drunk, presumably warm. It is noted that the broth is even better if a chicken has been cooked in the water first (i.e. chicken stock). Marcus Terentius Varro (116-27 BC) is acknowledged as the source for this description of beetroot broth, which occurs in later Roman versions of Apicius. Varro was a noted scholar, the first librarian of the public library in Rome, and was said to have written more than six hundred books on a wide range of subjects, including an important work on agriculture. The laxative recipes in Apicius are discussed further in Chapter Six. Varro's broth made with stock is a precursor of beetroot soups such as borsch.
The first boiled beetroots were probably the leftovers from the making of broth, but were then regarded as food in their own right. In a recipe for boiled beets (Betas elixans), they are said to be good to eat served with a dressing of mustard, a little oil, and vinegar. This appears to be an early beetroot salad, comparable to the modern beetroot salads described in Chapter Seven. While Flowers and Rosenbaum, Giacosa, and other writers translate Betas in this recipe as beetroot, however, others suggest that Apicius meant only beet leaves. Unfortunately, the text is unclear in this regard, although I favour the beetroot interpretation. Pliny the Elder (AD 23-79), in his Natural History, also suggested mustard dressing on beet, although again it may be to beet leaves rather than beetroot that he is referring. The oil/vinegar/mustard dressing, already used on beet leaves, may have been the first dressing used on beetroot.
Apicius included beets in recipes for soup, stew and stuffed sucking pig. In his barley soup, the leaves of beets (betae) and other finely chopped greens are added to a soup pot with legumes. Barley is used to thicken this soup, which is a forerunner of minestrone. In turnover stew, small white beets (albas betas) are boiled with leeks and various meats. Sucking pig stuffed with herbs is a recipe that derives from Apicius the gourmet. The stuffing includes meat from chickens and thrushes, snails, various sausages, stoned dates, flower bulbs, a wide range of herbs including beets (betae), peppers, pine kernels, fifteen eggs and liquamen sauce. The pig is sown up and smeared with wine, honey, oil, herbs and spices, before being roasted in a large oven. In this recipe, both the leaves and roots of beta may have been used.
It should be emphasised that the roots of Beta vulgaris were not commonly eaten as food in Roman times, while leaf beets were frequently part of a meal. However, the leaves of Beta vulgaris had a reputation for being somewhat insipid. Martial (Marcus Valerius Martialis, approximately AD 40-104), the writer of short poems, reflected this in a description of the crops growing on an estate outside Rome in one of his epigrams:
You could have seen there cabbages with noble heads
And leeks of either kind and lettuces like stools
And Beets that have some uses for a slow stomach.
Martial recommended a dressing of pepper and wine for beets.
Although Beta vulgaris appears to have been widely prescribed for its medicinal value, not everyone in the Roman world was convinced of its benefits. Pliny the Elder noted that although beets were easily digested, there were doctors who claimed them more harmful than cabbage. The influential physician Claudius Galen (AD 131-201) and Oribasius, the court physician to Julian the Apostate (Flavius Claudius Julianus, AD 332-363) were notable sceptics. Their view was that beetroot needed boiling twice, unless you wished to suffer from flatulence and stomach aches, that it was no more nutritious than any other plant of its kind, and that it was ineffective as a laxative. However, beetroot is still valued for some of the benefits extolled by the ancients, as we shall see in a later chapter.
Anthenaeus, writing in the third century AD, quotes Diphilus of Siphnos to the effect that the beet root was good in taste and a better food than the cabbage. Anthimus writing in the sixth century, within the same culinary tradition as Apicius, describes beetroot as being suitable for both summer and winter use. This presumably refers to both the leaves and roots in the summer, with the roots providing winter sustenance. The Romans probably took white and black beets to various parts of their empire, starting the spread of cultivated Beta vulgaris into northern Europe and beyond.
Beet appears in the gardens of Charlemagne (724-814), the ruler of an empire that included Gaul, Italy and large parts of Spain and Germany. In a 'Regulation concerning landed property' (Capitulare de villis), issued by Charlemagne around 812, Beta is registered as a plant to be specifically cultivated in the grounds of the Imperial estates. Beta vulgaris is well adapted to the cooler climate of Northern Europe; cultivated forms generally grow best under cooler conditions.
From Eastern Europe and the Middle East, cultivated Beta vulgaris was carried on trade routes to East Asia. Beets were consumed in Asia Minor in ancient times and in India by classical times, and were known in China by AD 850. Sturtevant notes that leaf beet (chard) is recorded in Chinese writing from the seventh, eighth, fourteenth and seventeenth centuries. In Asia, as in Europe, Beta vulgaris was originally cultivated for its leaves.
Leaf beet was a popular potherb from Roman times to the sixteenth century, although beetroot was much less frequently consumed as a foodstuff during this time. Beta vulgaris was grown for its roots throughout the Middle Ages, when it was usually referred to as Roman beet, particularly in monastery gardens in France, Spain and Italy. Medieval herbalists and gastronomes consumed beetroot and advocated its benefits.
Hildegard von Bingen (1098-1179) wrote down details for preparing beetroot. Hildegard is nowadays mainly revered for her sublime sacred music, but she was also an abbess, a healer with a good understanding of herbs, a writer, and something of a visionary. In her book Naturkunde, translated into modern German by Peter Riethe, she describes a white beet that needs to be peeled (therefore, a root). This is said to be more beneficial cooked than raw. Many of Hildegard's ideas were radical in her time, so her descriptions of beet root do not imply that it was widely consumed in the twelfth century. She also specified the roots of white beet, which has often been used medicinally but has rarely been eaten as food. Another key herbalist of the period, Albertus Magnus (c. 1200-1280) mentions a chard-like leaf beet, but not the roots of Beta vulgaris, in his observations on plants in the thirteenth century.
In contrast to beetroot, leaf beets gained in popularity during the Middle Ages. From the old Roman Empire, they flourished in cultivation throughout the Arab world. The Portuguese adopted the Arabic for beet (selg) as acelga or selga. Leaf beet was known as acelga by the thirteenth century throughout the Iberian Peninsula. Leaf beet, especially chard, is known today as acelga in Portuguese and Spanish.
Beet roots were long, thin and roughly turnip-shaped in the Middle Ages, rather than the swollen and succulent roots we know today. There is little written proof for the existence of fleshy roots in Beta vulgaris before the sixteenth century. After the Roman era, in fact, there is little mention of beetroot in manuscripts until the fourteenth century. Then the word Bete occurs in an English recipe of 1390. Barbarus (d. 1493) mentions a single, long, straight, fleshy, sweet root of beet that was good to eat. This description was reiterated by Ruellius writing in France in 1536 and Fuchsius in 1542. In his plant guide of 1919, Sturtevant notes how Fuchsius amends the description of Barbarus to include several branches and small fibres on the roots.
The fifteenth century Italian physician and gourmand Platina (Bartolomeo Sacchi), who has been described as the Dr. Atkins of his day, wrote his influential volume De Honesta Voluptate et Valitudine Vulgare (On Right Pleasure and Good Health) in 1460. This has been credited as the first modern cookbook, which sets out the basis for modern Italian cuisine and the ‘Mediterranean diet’. Platina included recipes for white chard, and a recipe for green sauce that includes leaf beet, parsley and wheat to thicken. He describes how beetroot, roasted in a coal fire, helps to sweeten the breath when it is eaten with garlic.
By the end of the fifteenth century, different cultivated forms of Beta vulgaris would have been found throughout Europe. In contrast to the Romans, who primarily took the root medicinally, from the sixteenth century onwards people consumed beetroot mainly as a vegetable. New beetroot varieties were developed that were suited to the table. From the 1530s onwards, detailed descriptions of beet roots start to appear. Caesalpinus distinguishes four types of beet in his book De Plantis of 1538, one of which had red roots. Matthiolus describes a new beet (Beta rubra) in Germany in 1558, which had red turnip-like roots that were good to eat. This beet was said to be quite distinct from the white and black beets commonly grown in Italian gardens of the time. These were among the first descriptions that specifically commented on the redness of the root. Pena and Lobel in 1570 also describe the new red beet, as related by Sturtevant, but they also note its rarity. Lobel illustrated the new beet in 1576 and emphasized its improved form, with the root being swollen at the shoulder.
The Italians developed different types of beetroot during the fifteenth and sixteenth centuries. A number of these early beetroot types were introduced into northern Europe from Italy by the sixteenth century. Camerarius describes a shorter and thicker form from Italy in 1586, for example, which might represent a prototype for cylindrical or half-long shaped roots. Daleschamp also records this type in 1587, in his Historia Generalis Plantarum. In addition, Daleschamp describes an important new improved long-rooted type known as Roman Beet (Beta romana). It is generally recognized as the prototype of modern beetroot, giving rise to both long turnip-rooted and stout globular-rooted varieties. Roman Beet was the first improved beetroot variety with a distinctly swollen root, for which there is good documentation. The name Roman Beet suggests that it originated in Italy. Its first recorded appearance, however, was in Germany in about 1558, followed by a description in England in 1576.
New beetroot types were enthusiastically cultivated in Germany, where gardeners played a key role in developing it from the late Middle Ages onwards and promoting it as a food. From Germany, beetroot's popularity as a root vegetable spread eastwards to Poland, Lithuania, Russia and the Ukraine, and northwards to Scandinavia. Beetroot started to become an important vegetable in Central and Eastern Europe by the end of the Middle Ages. It continues to be a staple today in this region, especially in rural areas. Its first use in Ukrainian and Slavic cookery is noted in cookery books dating from between the fourteenth and sixteenth centuries. Borscht, the classic beetroot soup from Poland, Russia and the Ukraine, originates from this time, as do other beetroot dishes such as Scandinavian herring and beetroot salad. Large long-rooted beetroots would have been harvested in the autumn for consumption during the winter.
In France, Ruellius described a new type of beetroot or betterave in 1536. This may be Roman Beet, which was known in French gardens by 1631, according to Sturtevant, growing under the name Beta rubra pastinaca. The French agronomist Olivier de Serres describes a type of beetroot in his Théâtre d'Agriculture of 1629 as, 'a kind of parsnip which has arrived recently from Italy'. He records that it has a very red and rather fat root, with thick leaves, and all of it is good to eat. He especially recommends the root as a choice food and notes that the juice it yields is like a sugar syrup, which is very beautiful on account of its vermilion colour. The cultivation of beetroot was described in the popular gardening book Le Jardinier Solitaire in 1612. Beet roots have been fed to cattle in France from the early 1600s onwards. Rouge Crapaudine or Crapaudine, one of the oldest known table beet varieties, was first cultivated in France. Its long roots have a distinctive black or dark purple, pock-marked and rough skin. La Varenne, who is credited with inventing the system used in modern French cookery, described the preparation of beetroot in his book La Cuisine Français in 1651. In his recipe, pre-cooked beets are peeled, cut into rounds, and fried in butter with a chopped onion and a dash of vinegar.
Roman Beet reached England in the late sixteenth century. John Gerard in his Herball or The Historie of Plants, first published in England in 1597, notes the distinction between white beet (Beta alba) and red beet (Beta rubra) and provides an early description of Roman Beet. All cultivated forms of Beta vulgaris were called beet in Gerard's day. Up until the Elizabethan era in England, white beet was the only type of cultivated Beta vulgaris commonly grown.
John Gerard (1545-1612) was the superintendent of Lord Burleigh's garden in central London, amongst other things. His views on plants were highly respected and Queen Elizabeth I was said to have had a high opinion of him. It was also said that Shakespeare, who lived around the corner from Lord Burleigh’s garden for a number of years, might have been inspired by the plants in it when writing his early plays. Gerard’s Herball was updated in 1633 by Thomas Johnson.
In the Herball, Gerard describes the common white beet as having great broad leaves and large, thick and hard roots. It is clear from his description that the white roots of this plant were not consumed as food. Gerard described the cooking of leaves of white beet, 'a cold and moist pot-herbe', which 'quickly descendeth' or wilts when boiled. He concludes that it 'nouristheth little or nothing'.
Gerard explains how a merchant, Nicholas Lete of London, gave him a novel type of red beet from a place beyond the seas, although that place is not named. He grew it in his garden in 1596. Gerard describes this red beet, 'which hath leaves very great, and red of colour, as is all the rest of the plant, as well as root, as stalke, and floures full of a perfect purple juyce tending to redness: the middle rib of which leaves are for the most part very broad and thicke, like the middle part of the cabbage leafe, which is equall in goodness with the leaves of the cabbage being boyled'. He suggests that the greens of this red beet 'may be used in winter for a sallad herbe, with vinegre, oyle and salt, and is not only pleasant to the taste, but also delightful to the eye'. Gerard then refers to the greater red Beet or Roman Beet, which he regards as distinct from the novel red beet just described.
On Roman Beet, Gerard writes that, 'boyled and eaten with oyle, vinegre and pepper, is a most excellent and delicat sallad: but what might be made of the red and beautifull root (which is preferred before the leaves, as well as beautie as in goodness) I refer unto the curious and cunning cooke, who no doubt when hee had the view thereof, and is assured that it is both good and wholesome, will make thereof many and divers dishes, both faire and good'. Gerard therefore recognized the potential of beetroot as a vegetable.
One detail of Gerard's description of his novel red beet or chard (which he saw as distinct from Roman beet) has sown much confusion. He describes the plant that he grew from material the merchant gave him and records that it grew to eight cubits in height. Some commentators have taken this to be the height of the green tops, which is a very improbable height. However, it refers to the height of the long flower spike put out at the end of beetroot’s second year of growth, on which the seeds form. This is undoubtedly a very long flower spike. A cubit is around 45 cm and so Gerard’s flower spike is 360 cm or 12 feet in height. Beta vulgaris flower spikes can easily reach 120 cm or 4 feet in height. However, 360 cm or 12 feet is an exceptionally tall flower spike. Some writers have wondered if the spike was measured correctly or whether Gerard was exaggerating. Even in its day, Gerard's Herball was known to be error-ridden, and we should take his description with a pinch of salt. It is probable, however, that his novel red beet bolted and set seed prematurely. Its roots are depicted as being long and thin in an illustration in the Herball. Gerard gave some of the seeds of the novel beet to his friend John Norden and kept some himself. They both found that, although the original plant was only red, the seeds produced plants of 'many and varied colours'. This variation is till typical of unimproved coloured chard today.
John Parkinson (1567-1650), who knew Gerard, sheds more light on varieties of beet in A Garden of Pleasant Flowers: Paradisi in Sole Paradisus Terrestris (1629), probably the most famous English gardening tome of the seventeenth century. Incidentally, the title contains a pun of the author’s name (Park in Sun). Parkinson was apothecary to King James I and later the first royal botanist to Charles I. He notes a number of varieties of beet in England by 1629: 'some white, some green, some yellow and some red. The leaves of some are of use only, and the root not used, others the root is only used and not the leaves'.
The common white beet was the most common type known in England up until this time. It is the same white beet known to the Greeks and Romans, which was originally found in Sicily. Only the leaves are eaten as food. Parkinson describes it as having many great leaves next to the ground, of a whitish-green colour. The flower stalk of this chard is great, strong, ribbed and crested, bearing leaves and flowers. The flowers are small pale green and give prickly seeds. Parkinson describes the root as being, 'great, long and hard', and being of no use at all.
Parkinson describes a green beet, in addition to white and red beet. This is said to be like white beet, but with a darker green colour. John Tradescant found it on the salt marshes near Rochester. There is a possibility that this could be a form of wild sea beet, which is known to grow in maritime marshes in parts of England.
Parkinson differentiates between the common or small red Beet and the larger Roman red Beet. He suggests that the small red beet is a direct descendent of the black beet known to the Romans. The small red beet is used for its leaves and not its roots. Parkinson describes that it, 'differeth not from the white Beete, but only that it is not so great, and both the leaves and roots are somewhat red'. The leaves of some plants are redder than others. Some plants only have red leaf veins, while others have dark red leaves. Parkinson concludes his description of common red Beete by noting, 'The roote hereof is red, spongy, and not used to bee eaten'. The common red beet is therefore a chard that differs from the white variety mainly in colour.
The Roman Beet is used for both its leaves and roots. Parkinson's account makes it clear that it is the first beetroot to be utilized in England. Romane red Beete is, ?the most excellent Beete of all others: his rootes bee as great as the greatest carrot, exceeding red both within and without, very sweet and good, fit to be eaten'. Parkinson describes how this beet grows higher than common red Beet, while the leaves have a better taste. The roots of Roman Beet are said to sometimes be short like a turnip and sometimes long like a carrot. The seed is said to be like that of small red Beet.
Another variety of beet decribed by Parkinson is Italian Beete, but this classification seems to have been erected mainly to encompass the, 'great red Beete that master Lete a merchant of London gave Master Gerard'. He repeats Gerard’s description of the great leaves and makes no mention of the roots.
Parkinson describes how the leaves of all the types of beet described can be put into the pot among other herbs to make pottage. They can also be boiled whole and served with meats, which he notes is popular in France and England. He notes the roots of the common red Beet are used by some adventurous cooks, but are not usually eaten. However, the roots of Roman Beet appear to be a new fashion in 1629, 'the Romane red Beete is of much use among cookes and is grown of late dayes into a great cuftome'. Cooks used them to garnish dishes of meat and fish and may have used it to colour dishes also. He describes how, 'rootes of the Romane red Beete being boyled, are eaten while hot with a little oyle and vinegar'. It is accounted a delicate salad for the winter, which can also be eaten cold.
In his celebrated Herbal, Nicolas Culpeper (1616-1654) adds little to the descriptions of beet made by Gerard and Parkinson, but he does compiles an extensive list of medicinal uses of chard and beetroot. In The English Physician, or Herball (1653), Culpeper notes that White Beet and Red Beet are the two best known sorts of beet. For White and Red Beet, Culpeper repeats the descriptions found in Parkinson. He does not mention Roman red Beet, but as a doctor he was interested in readily available herbal remedies rather than food plants. The medical uses of beet described by Culpeper are considered in Chapter Six. Incidentally, medical herbals from Germany from this time had started linking plants and astrology. Culpeper followed this practice, becoming a trained astrologer. In his Herball, white beets are considered to be under the influence of Saturn, while red beets are under Jupiter.
While Roman red Beet appears to have been newly fashionable when Parkinson wrote his famous book, by the time Robert May wrote The Accomplisht Cook in 1660 it appears to have become an established vegetable in England. John Evelyn in his book Acetaria of 1699 writes that cold slices of boiled beetroot make a 'grateful winter sallet' eaten with oil and vinegar. He adds that the French and Italians had contrived beetroot into curious figures to adorn their salads.
Jane Grigson notes that around 1760 the word vegetable starts to be used in its modern sense, as a herb or root grown for food. Vegetables at this time were no longer mainly seen as medicinal herbs or the preserve of herbalists, but as pleasurable food in their own right. However, the idea that vegetables are good for us has persisted to the present day, with sound reason. Beetroot became one of the plants listed for vegetable growers in what evolved into the seed catalogue. Lovell had listed Red Roman Beet in 1665, although in 1726 it was still the only type of beetroot listed in England by Townsend the seedsman. However, Sturtevant notes that Mawe and Bryant both listed a second type, Long Red, in 1778 and 1783, respectively. This variety is also referred to as called common Long Red and was described by Vilmorin in 1885 as Long Blood Red.
Back in Italy, gardeners were cultivating distinct varieties of beetroot. Bassano was found in all Italian markets by 1841. Vilmorin described it in 1885. It has a prototypical cylindrical or flat-bottomed red root and it may be the prototypic cylindrical beetroot described by Camerarius and Daleschamp in the late sixteenth century. Cylindrical beetroot are also referred to as intermediate because they are believed to have been a halfway stage between the original long-rooted beetroot and modern globe-rooted varieties. Bassano was named after a town in the Venetian Alps. Incidentally, the town of Bassano is also famous for its asparagus, which has been grown there since the sixteenth century. Another early Italian variety of beetroot is Barabietola di Chioggia, which was first grown in market gardens around Venice around the sixteenth century. This variety has a distinctive red and white circular bullseye pattern. The town of Chioggia is situated at the southern end of the Venetian lagoon and is a major fishing port on the Adriatic. Beetroot was cultivated here many centuries ago, in sight of the sea, under conditions similar to those where its wild ancestor is still found.
Beetroot varieties were also developed in other European countries. The white-fleshed Blankoma, for example, was an early Dutch introduction. Dutch plant breeders have subsequently produced many new beetroot varieties, including Bikores, Libero and the recent hybrid Pablo.
During the sixteenth and seventeenth centuries, uncontrolled hybridization between leaf beets, chards and early long-rooted beetroot produced a wide variety of forms. Beta vulgaris is primarily outcrossing and reproduction is by cross-fertilization rather than self-fertilization. This favoured a wave of hybridization, providing the raw material from which modern beetroot varieties have arisen. Roman Beet and possibly other early long-rooted types became variable in leaf and root morphology due to hybridization with leaf beets, chards and other beetroot. Root shapes other than long appeared and where selected for in gardens. By the nineteenth century, a wide range of cylindrical, flat and globular varieties were introduced to growers, particularly in Northern Europe. Cylindrical forms are also called intermediate, because their root shape is midway between long-rooted and globular.
In comparison to beetroot, leaf beets have been relatively unchanged since ancient times. The word chard derives from the Latin and French words for thistle (chardon, charde), an unrelated plant to Beta vulgaris. The French writer Bauhin describes, in 1596, dark (black), white, red and yellow chards, along with chard having a particularly broad stalk, and wild sea beet. His chards were very similar to coloured chards described by writers in the ancient world. From the start of the 1800s, however, plant breeders started to produce a range of improved chard varieties. These types became more compact in appearance through selective breeding.
Although initially adopted to describe broad-stemmed leaf beet, chard gradually became a generic term used to describe the succulent stalks or leaf petioles of globe artichoke, cardoon and other vegetables. The term Swiss chard derives from nineteenth century seed catalogues. The Swiss pre-fix was used to distinguish Beta vulgaris with broad leaf petioles from other plants labelled generically as chard. It is unclear why chards were considered to be Swiss, although some commentators suggest that it was the Dutch who were responsible.
In 1885, Vilmorin describes White, Swiss, Curled Swiss, Silver and Chilean varieties of chard. These are described as being vegetables for the table and as garden ornamentals. Silver or silver-leaf chard (Poiree blonde a carde blanche Vilmorin 1883) is described as a light green form of Swiss chard, with shorter and much broader leaf stalks. Chilean chard is a form usually grown for ornamental purposes. They have very broad leaf stalks that are often twisted. The leaves can be puckered like a Savoy cabbage, as also occurs in Curled Swiss chard. Ornamental Chilean chard was probably introduced in Belgium in the early to mid nineteenth century.
Only one variety of beetroot was listed in the USA prior to 1806, a long-rooted red beet in McMahon's seed catalogue. However, Sturtevant noted that, in 1826, Thorbum had listed four varieties in the USA: Long Red, Bassano, Egyptian or Flat Egyptian and Detroit. The Long Red appears to be the same variety recorded in England since 1778. Bassano was imported from Italy, where it was commonly grown over a hundred years previously. Flat Egyptian is an American production, although it may be derived from material originally imported from Egypt and the Middle East. It was first grown around Boston in about 1869. Detroit is another American-bred variety, which was introduced in 1897 and is still widely grown today. Detroit can be used as a winter crop, or harvested young as a summer crop. When Detroit arrived in Britain and several other European countries by 1900 it helped to establish the trend toward small-rooted beetroot being grown as a summer crop for salads.
Improved beetroot varieties were relatively slow in reaching Britain. Only two kinds, Red Roman and Long Red, were available from English seed merchants prior to 1800. In the seventeenth century beetroot was viewed as a sweet novelty food. A recipe for crimson biscuits of red beetroot survives from the eighteenth century. The British really took to beetroot, however, in the Victorian era, when it became popular as a salad vegetable. The juice of beetroot was also used as a hair rinse and a dye for fabric. A nineteenth century English vegetable garden has been reinstated at The Lost Gardens of Heligan in Cornwall, England. The gardens of the Heligan estate went into decline during after the First World War, but were restored from a condition of extreme neglect during the 1990s. The productive garden has been lovingly restored with vegetable varieties that would have been grown in the estate’s heyday. The main beetroot varieties (all pre-1880) cultivated are the long-rooted Cheltenham Green Top, the French variety Crapaudine, the tapering cylindrical-rooted Cylindra, the early American varieties Detroit Globe and Burpee’s Golden, and the Italian variety Chioggia.
Up until the twentieth century beetroot has primarily been grown as a winter root vegetable. Large-rooted maincrop beetroot, including tapered and globe varieties, give heavy yields and can be lifted late in the season for use during the winter months. Large-rooted maincrop beetroot has been eaten as a staple for many years in Central and Eastern Europe. However, during the late twentieth century, beetroot has increasingly been regarded as a summer crop. Smaller-rooted varieties have been bred and cultivated primarily as a salad vegetable. Smaller globe-shaped beetroot have become predominate in many areas as a summer crop, because they mature early, grow rapidly and produce good yields.
Beetroot varieties exist that are early, medium and late maturing. Therefore, beetroot can now be grown for most of the year. With the popularity of summer beetroot increasing after the Second World War, however, a large proportion of the crop was boiled and pickled. This made beetroot become practically synonymous with beetroot pickled in malt vinegar, especially in Western Europe between the 1950s and the 1970s. Thankfully, this is now changing, and later in the book we will see how the culinary uses of beetroot are now more diverse than ever before.
All parts of Beta vulgaris have almost certainly been fed to livestock since at least Roman times. Beetroot was the first cultivated type of Beta vulgaris to be selected for its swollen roots. There was no distinguishable fodder beet or sugar beet until the eighteenth century and, therefore, all swollen-rooted Beta vulgaris before this time are considered as beetroot or beet. The tops and roots of beetroot have mainly been grown for fodder in recent centuries in France, Germany and several other countries. In countries with cooler climates, large white-fleshed varieties have been preferentially chosen for storage for fodder during the winter. The breeding of selected lines of Beta vulgaris especially to feed to cattle and other animals, however, started in relatively recent times.
The Abbé de Commerell wrote the first known description of beet being grown and specifically fed to cattle in 1787. He referred to mangel (Runkelrübe) being used as fodder beet in the Rhineland in the 1750s. Mangel derives from a yellow type of beet with good winter storage properties. This large winter beet soon became cultivated around Europe as a fodder beet. Mangel wurzel was also being cultivated in North American by 1806.
Mangel or mangel-wurzel probably first originated through a cross between a yellow-rooted beetroot and a leaf beet. Vilmorin describes at least sixteen kinds of mangel in the late nineteenth century. Mangels are regarded as too coarse in texture for human consumption. The roots, and also the leaves, however, provide a nutritious food for cattle, which can be produced abundantly and relatively cheaply. Fodder beet is generally preferred to carrot and turnip for livestock. Recent crosses between mangel with sugar beet have produced modern fodder beet cultivars.
In commercial terms, sugar beet is the most important cultivated form of Beta vulgaris. It was recognized in the sixteenth century that a sweet syrup could be extracted from the swollen roots of beet. From the mid-eighteenth century, beetroot with large roots and white flesh were being grown in the German regions of Magdeburg and Halberstadt, and in Silesia. These beetroot had been selected for their sweetness and large size. The Russian chemist Andreas Sigismund Marggraf (1709-1782) discovered that crystals from syrup extracted from Silesian beet were identical to crystals obtained from sugar cane. In both cases, the sugar crystals were pure sucrose. Marggraf was an eminent scientist and the President of the Berlin Academy of Sciences. He presented his results to the Academy in 1747 and the proceedings of this meeting were translated into French two years later. The amount of sugar obtained by Marggraf from beet was relatively low, however, and at the time it did not seem worth extracting commercially.
Marggraf's student, Franz Carl Achard (1753-1821), was the first person to select and process beets specifically to produce sugar. In a garden in Kaulsdorf, a village near Berlin, he grew different types of beet to determine which would be the best to develop for sugar extraction. He compared a range of beets that were used to feed livestock in southern Germany and found that conical-shaped roots, with white skins and white flesh, yielded the highest amounts of sugar. He also showed that soil type, growing conditions and cultivation methods influenced the root’s sugar content. Initially Achard found great variability in the plants produced from selected seed, but after a few years he obtained a line that consistently produced higher levels of sugar than previously recorded. This selected line was called White Silesian Beet and it is the ancestor of all modern sugar beet cultivars.
Achard presented the King of Prussia, Frederick William III, with a sugarloaf made from beet in 1799 and requested the funding necessary to start large-scale sugar production. In 1801, the King gave Achard the money to purchase an estate in Cunern in Lower Silesia. The first sugar beet processing factory was set up there in 1802. Despite technical difficulties and delays, Achard obtained levels of sugar (around 4 to 6% in fresh roots) that were sufficient to attract commercial interest. This launched sugar beet as a commercial crop.
A friend and neighbour of Achard, Moritz Baron von Koppy, built a much larger sugar beet processing factory at Krayn, near Cunern, in 1805. Koppy established cultivation methods for sugar beet, improved the efficiency of its processing, and found uses for the by-products of processing. The tops, beet pulp and molasses were fed to animals, for instance, while the dried pulp made a coffee substitute and alcohol obtained from the molasses was used to make vinegar. Achard summarized the knowledge gained by himself and Koppy in a widely-read book.
Sugar beet is therefore a relatively recent crop. At the start of the nineteenth century, all Europe's sugar was obtained from sugar cane grown on plantations in the Americas. The slave revolts in the plantations of Santa Domingo in the 1790s, however, were the first sign that supplies of imported cane sugar could not always be relied upon. The flow of sugar could be disrupted, while a sense of unease in was starting to develop in parts of Europe about a system that relied on slavery.
The sugar beet industry in Europe effectively started in France and Belgium in 1811, at the instigation of Napoleon Bonaparte. His economic plan for continental Europe, in the first decade of the seventeenth century, placed an emphasis on developments that reduced imports of goods supplied by British colonial trade, including sugar cane. Napoleon's army was occupying Silesia in around 1810 and he fully exploited the advances being made there in sugar beet production. A French Commission had confirmed Achard’s findings and presented Napoleon with loaves of beet sugar in January 1811. Later that year, Napoleon instigated a policy that rapidly increased beet sugar production in France and in countries under French control. In 1811, around forty small beet factories, mainly in France and Germany, were established. This indigenous source of sugar soon became of strategic importance to Napoleon, because English naval blockades stopped imports of cane sugar from the West Indies reaching France during the Napoleonic Wars.
After the decline of the Napoleonic Empire, from 1813 onwards, the rapid spread of sugar beet cultivation was stopped, and cane imports were resumed. However, sugar beet cultivation, albeit over much smaller areas, continued in France and Germany. The French experimented with different lines of beet derived from Achard's original selections. By 1824, five types of beet selected for sugar production were described (grosse rouge, petite rouge, rouge ronde, jaune and blanche). A distinction was made during the 1830s between types of forage or fodder beets (Runkelrübe) and types of sugar beet (Zucherrübe)
The plant breeder Louis de Vilmorin (1816-1860) discovered that sugar beet root extracts of high density yielded more sugar, enabling him to devise a method using specific gravity to quantify sugar content in comparison with solutions of known sugar concentration. In 1852, this technique was modified into the silver ingot method, which became a standard for measuring the sugar content of beet juice. The polarimeter - a device to measure the optical properties of liquids - was also invented around this time; the amount of sugar in beet juice being quantified using the Ventzke scale, named after the its inventor. Vilmorin and other plant breeders were able to make rapid progress in improving sugar beet through continuous selection using these new techniques. From the 1830s, beet sugar production again increased in France and Germany. By the 1870s, numerous beet factories had been established throughout central and eastern Europe.
Sugar beet has been cultivated continuously in Germany since the time of Achard. Systematic plant breeding soon led to the production of improved varieties in the latter half of the nineteenth century. A new variety called Imperial was produced in around 1860 near Halle, for instance, which had a uniform appearance and a relatively high sugar content (11-13%). By 1880, breeding programs in France and Germany had resulted in sugar beet with up to 18-20% sugar per fresh weight of root. This is an acceptable level of sugar by today's standards. Around the 1880s, however, the aims of plant breeders diverged. Raising sugar yield ceased to be the only goal for sugar beet improvement. The different types of sugar beet that were subsequently produced will be considered in the following chapter.
Sugar beet cultivation started in the USA in the 1830s, when German and French immigrants arrived bringing the necessary technology with them. By the 1890s, sugar beet processing facilities had been established in California, Nebraska, Utah and Colorado. A large expansion US beet sugar occurred in 1900. By the 1990s, around 8% of the world's total sugar beet crop was grown in the USA. However, this area is now declining, due to the increased importance of corn syrup and sweeteners obtained from maize.
Sugar beet production started later in other European countries. In England, for example, the first sugar beet was cultivated in 1920s, although it is now a major crop that is focused on Suffolk. Today, sugar beet is grown throughout Europe and in North America.
In 1900, more of the world's sugar (sucrose) was produced by beet (63%) than from cane. However, this peak in the proportion of sugar produced by beet was followed by a relative decline due to an international agreement in 1901 that stopped import taxes being levied on cane sugar. Today, around two-fifths of the world's sugar is produced from sugar beet. Sugar beet still has an advantage over sugar cane, in that it grows in temperate regions where consumption of sugar is highest. Indeed, sugar consumption in industrial counties skyrocketed in the late twentieth century. This has been one factor in the dramatic increase in rates of obesity observed, especially in North America.
The rise of alternative sweeteners, a public health backlash against excessive sugar in foodstuffs, and a surplus of sugar beet in the expanded European Union of 2004 are among the factors that have placed sugar beet cultivation at a crossroads. However, new and diversified markets should ensure that it continues to be an economically important crop well into the future. Brazil first grew sugar beet for ethanol production (gasohol) in 1979. Its use to make biofuel and other industrial products is set to increase.
Sugar beet was one of the first crops to be genetically modified. Biotechnology is being utilized to produce a range of novel sugars and proteins in sugar beet. The future prospects for modifying Beta vulgaris will be examined further in Chapter Four. Beetroot, meanwhile, continues to enjoy a revival as a healthy, wholesome and no-nonsense vegetable. In later chapters, its health benefits and culinary versatility will be explored. Its future looks rosy.



Achard, F.C. (1809) Die europeche Zuckerfabrikation aus Runkelrübe, in Verbindung mit der Bereitung des Brandweins, des Rums, des Essigs, und eines Coffes Surrogats aus ihren Abfen. Leipzig: J.C. Hinriches (Reprinted: 1985. Berlin: Verlag Bartens).
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© Copyright Stephen Nottingham, 2004

sf.nottingham@btinternet.com






July 2004, February 2006. SFN.
1

Beetroot: 3. Classification and Botany


Beetroot (2004)

Stephen Nottingham

© Copyright: Stephen Nottingham 2004




3. Classification and Botany 
Beetroot (beets) are classified, like all living organisms, in terms of class, order, family, genus and species. Beets are flowering plants and therefore within the class Dicotyledonae. Within this class, they are part of the order Caryophyllales. Within this order, beets are part of the Chenopodiaceae family. The Chenopodiaceae or goosefoot family of plants also includes other edible species, including spinach (Spinacia oleracea), quinoa (Chenopodium quinoa), orache or orach (Atriplex hortensis) and Good King Henry (Chenopodium bonus-henricus). Beets are in the genus Beta and the species Beta vulgaris. The cultivated forms of Beta vulgaris are leaf beets (spinach beet and chard), beetroot (table beet or garden beet), fodder beet and sugar beet. This chapter explains how beets are classified within the genus Beta. The chapter concludes with a closer look at the different forms of cultivated beet.
The Swedish botanist Linnaeus (Carl Linné, 1707-1778) described the species Beta vulgaris L. in 1753. He erected the genus Beta L. specifically to incorporate this species. Linnaeus' name is therefore given as the authority for the genus and species; it is usually abbreviated (L. or sometimes Linn.).
The genus Beta probably first originated in Mediterranean Europe, diversifying and spreading northward and eastward in prehistoric times. A secondary region of Beta biodiversity developed in the Near East. Annual, biennial and perennial plants occur in the genus.
A section is a taxonomic subdivision of a genus. Sections were first erected within the genus Beta in 1927. Different authors have modified these sections over the years. The original three sections described were Vulgares, Corollinae and Patellares. Today, four sections are used to classify all the plants within the genus Beta. These four sections are Procumbentes (formerly Patellares), Nanae, Corollinae and Beta (formerly Vulgares). At present, within the genus Beta, these four sections encompass ten species and three subspecies.
The oldest of the four sections in evolutionary terms is Procumbentes. Botanically, Procumbentes is distinguished by having hard round black fruits (seed clusters) lacking the perianth segments that result in plants in other Beta sections having 'corky' fruit with irregular shapes. The section contains three species: Beta patellaris Moq., Beta procumbens Chr. Sm., and Beta webbiana Moq.. These species are all perennial (under favourable conditions), with very short vegetative phases. They are distinguished from each other by leaf shape: Beta patellaris having the broadest stem leaves and Beta webbiana the narrowest. The centre of diversity for Procumbentes is the Canary Islands.
Beta patellaris (referred to as Beta campanulata by Vilmorin in 1923) is found in patches (up to 1.5 m diameter) in coastal and low-lying dry rock areas throughout the Canary Islands, and also in south-east Spain, near Almeria, and some coastal areas of Morocco. It has small white twisted roots, and a chromosome number of 36.
Beta procumbens has a very limited distribution, being virtually restricted to the Canary Islands, particularly Tenerife, Gran Canaria, Gomera, La Palma and Lanzarote. Isolated populations might still exist in southern Portugal and north Africa. The plant has small white twisted roots and a chromosome number of 18.
Beta webbiana is virtually restricted to Tenerife, Gran Canaria and Fuerteventura in the Canaries. Isolated populations might still exist in southern Portugal and north Africa. It has very long fibrous roots and a chromosome number of 18.
The only species in the section Nanae is Beta nana Boiss & Held. It is endemic to Greece and has a distribution that is restricted to snowy patches on the Greek mountains Olympus, Parnassos, Giona and Taiygetos in Greece. This plant is endangered and is protected within nature reserves. Nanae is distinguished from other sections due to a short inflorescence (only up to 10 cm) and its solitary flowers. Beta nana is a small perennial plant, with a stout cylindrical root and a chromosome number of 18.
Plants in the section Corollinae are hardy perennials with strongly sclerified roots. Their distribution is centred on Iran and Asia Minor. There are currently three species recognized in this section: Beta lomatogona Fischbeck & Mey, Beta macrorhiza Stev. and Beta corolliflora Zoss.
Beta lomatogona is distinguished within the section by having flowers that are usually solitary. It is found at relatively high altitudes, primarily in Anatolia, Armenia, Azerbaijan, Iran and south-east Turkey, in steppes, arid-stony mountain sides, dry wastelands and in agricultural land. Beta lomatogona has a chromosome number of 18. The former species Beta intermedia Bunge is now thought to be an apomictic type of Beta lomatogona having a chromosome number of 45.
Beta macrorhiza is a perennial that develops a bushy habit with maturity. It is distributed in mountainous regions of Armenia, northern Azerbaijan, Dagestan and south-east Turkey, typically in dry river beds and disturbed ground. It has a chromosome number of 18.
Beta corolliflora is a perennial that has a pyramidic growth habit. It is found in central Anatolia, Armenia, Georgia and western Azerbaijan, at high altitude (1300-2450 metres), on stream banks, in meadows and in moist disturbed land, including farmland. It has a chromosome number of 36. Two types of Beta corolliflora exist, the other being the former species Beta trigyna Wald. & Kit., which is now considered an apomictic hexaploid (54 chromosomes) close to Beta corolliflora.
The Beta section of the genus Beta contains all the cultivated forms of Beta vulgaris and the wild sea beet from which they are descended. The section contains three species: Beta macrocarpa Gussone, Beta patula Aiton and Beta vulgaris L.. There are currently three subspecies (subsp.) recognized in this section: Beta vulgaris subsp. adanensis (Pamukuoglu) Ford-Lloyd and Williams, Beta vulgaris subsp. maritima (L.) Arcangeli and Beta vulgaris subsp. vulgaris L.. The distribution of plants within the section Beta is centred on the eastern Mediterranean region.
Beta macrocarpa is an annual with a short vegetative phase, with long, ovate, glabrous (smooth) green leaves. The glomerules (flowers) cluster on the inflorescence in groups of around three. It is found in southern Portugal, southern Spain, the Balearic Islands, the Canary Islands, Morocco, Algeria, southern France, Greece, Cyprus, Israel and Turkey. Beta macrocarpa is a fairly common species, for instance, in field margins and along roadsides. It is also halophytic (salt tolerant) and found in particular saline habitats, such as salt marshes in Portugal and salt mine workings in Portugal and the Canary Islands. The chromosome number is usually 18, although natural polyploidy has resulted in Canary Island populations having a chromosome number of 36.
Beta patula is a perennial, under favourable frost-free conditions. It has small glabrous leaves and is distinguished botanically from the other two species in the section Beta by having flower clusters of around seven. Beta patula has a very limited distribution, being found only on Illheu dos Embarcaderos - a small island near Madiera. It has a chromosome number of 18. Beta vulgaris subsp. adanensis is an annual, and also a perennial under favourable (frost-free) conditions. It has long wedge-shaped leaves and glomerules in groups of around three that are spaced out along the inflorescence. It is found in Greece, Cyprus, Turkey and Syria. The chromosome number is 18.
Beta vulgaris subsp. maritima or sea beet is the ancestor of cultivated beet. It can grow as a biennial or a perennial, under favourable (frost-free) conditions, although many Mediterranean populations are annuals. It has long wedge-shaped leaves in a rosette arrangement and is without a swollen root. The glomerules occur in groups of around three and are crowded together on the inflorescence. It is further differentiated from subsp. adanensis through its smaller glomerules and flowers that are less flat. It has a chromosome number of 18.
Sea beet occurs throughout the Mediterranean region, along Atlantic coasts up into Scandinavia, throughout the Near and Middle East, and into India. It thrives on stony and sandy beaches, rocky cliffs, coastal grasslands, and salt marshes. Sea beet is also found in some inland sites in the Mediterranean region, and in Iran and Azerbaijan.
Beta vulgaris subsp. vulgaris is cultivated beet, in all its forms. Cultivated beets are considered in terms of Cultivar Groups later in this chapter.
All plants within the section Beta can readily interbreed. Wild and cultivated plants in the genus Beta are outbreeding. This means that they are more likely to fertilize other compatible plants (cross-fertilization) than to fertilize themselves (self-fertilization). They share a mechanism, called the S-allele incompatibility system, which acts to prevent self-fertilization. A continuous variation in morphology within the section Beta would therefore exist, if genetic lines were not preserved through artificial selection and cultivation.
Interbreeding is rare between plants in different sections of the genus Beta. One reason for this is the differences in chromosome number in different sections. Chromosome number varies through polyploidy, the presence of extra sets of chromosomes in the nucleus. For the genus Beta, the chromosome number possibilities are 9 (haploid), 18 (diploid), 27 (tetraploid), 36 (triploid), 45 (pentaploid) or 54 (hexaploid). Beta vulgaris in the Beta section has a chromosome number of 18, but chromosome number varies in other sections. Plant breeders have found it easier to cross Beta vulgaris with plants in its own section. Wild sea beet has contributed genes to many modern sugar beet cultivars, for example, such as resistance to the fungal disease Cercospora. However, important sources of pest and disease resistance have been identified in plants in the Procumbentes and Corollinae sections. After much experimentation, some of these genes have been bred into cultivated Beta vulgaris. Beet cyst nematode resistance, for example, has been transferred from Beta patellaris to sugar beet.
The incompatibility system than maintains outbreeding has been known to break down naturally, however, in isolated annual populations of wild beet in the genus Beta. Plants within these populations can therefore be self-fertilized. Small populations of predominantly inbreeding wild beets can be found in isolated locations throughout the Mediterranean. New species of wild beet have been described from such populations.
There are two approaches to classifying cultivated plants such as Beta vulgaris. The first is the taxonomic system called binomial nomenclature and the second is the more flexible horticultural classification system.
The system of classification, in which organisms are assigned to class, order, family, genus and species, is called binomial nomenclature. This system was devised by the Swedish botanist Linnaeus (Carl Linné 1707-1778). Binomial nomenclature can be extended below the species level (infraspecific classification), by including the ranks of subspecies (subsp.) and variety (var.).
Strict rules are applied for binomial nomenclature. For plants, these rules have most recently been laid out in the International Code of Botanical Nomenclature (ICBN), which was adopted by the International Biological Congress in 1981 and published in 1983.
Binomial nomenclature has been very successful in cataloguing the world's biodiversity, but its use below the species level may not always be appropriate for cultivated plants. By definition, a species is a group of organisms that interbreed. Populations of a species can become separated due to geographic isolation or other factors. Such populations can develop different characteristics, under different selection pressures, and become distinct subspecies. Subspecies, by definition, must resemble each other and, as a group, have characteristics that distinguish them from other subspecies. Organisms within a subspecies breed more freely among themselves than with other members of the species. Eventually a new species may arise through speciation. This has occurred for wild beets in the genus Beta, particularly in the Canary Islands. However, it has been artificial selection, rather than natural selection, that has driven the evolution of cultivated beets. This can be problematic for classification when cultivated forms, assigned to different categories, can freely hybridize in the field.
When Linnaeus first described Beta vulgaris in 1753, he erected three varieties within the species: wild ancestral beet Beta vulgaris var. perennis, leaf beet Beta vulgaris var. cicla, and garden beet Beta vulgaris var. rubra.
In 1763, Linnaeus decided that wild maritime or sea beet should be a separate species, Beta maritima L., and the varietal name perennis was discarded. Taxonomists have since brought sea beet back into the Beta vulgaris species. Sea beet is now considered a subspecies: Beta vulgaris subsp. maritima (L.) Arcangeli. Its classification as a subspecies is appropriate because of the ease with which it cross-breeds with cultivated Beta vulgaris, and the insufficiently discontinuous morphology between it and cultivated forms within the genus Beta to warrant it being a separate species.
Linnaeus' division of Beta vulgaris into leaf beets (cicla) and root beets (rubra) has persisted; although since Linnaeus' day, fodder and sugar beets have caused the root beets to be further sub-classified.
For many years, the distinction between leaf and root beets was raised to the subspecies level. Artificial selection has exacerbated the morphological differences within Beta vulgaris, and this was thought to represent real morphological, genetic and geographic discontinuity within the species. An emphasis on the leaves gave rise to Beta vulgaris subsp. cicla. The name 'cicla' derives from Sicula, the name Theophrastus originally gave to leafy beets from Sicily. Selection for a single swollen taproot gave rise to Beta vulgaris subsp. vulgaris. However, the current taxonomic situation is that all cultivated forms of Beta vulgaris belong to just one subspecies: Beta vulgaris subsp. vulgaris.
In taxonomic schemes, variety (var.) is the level below subspecies. A variety is a group of individuals that differ distinctly from but can interbreed with other varieties of the same species. The characteristics used to classify a variety must be genetically inherited. In Linnaeus' day, fodder beet and sugar beet were considered to be beetroot. Today, all the different cultivated forms of Beta vulgaris subsp. vulgaris are distinguished at the variety level. Chard is Beta vulgaris var. cicla, beetroot or table beet is Beta vulgaris var. conditiva, fodder beet is Beta vulgaris var. alba, and sugar beet is Beta vulgaris var. altissima (formerly esculenta).
In a recent taxonomic key of the genus Beta, the authors (Frese et al.) quote Paul Aellen, writing in 1938: "Studies on Beta are getting more difficult the more you plunge in the matter". The taxonomy of Beta has been modified numerous times since Aellen wrote these words and the situation is still fluid. However, recent genetics studies are helping to clarify the situation. The classification of wild species in the genus Beta has recently been rationalized and the overall number of species in the genus has been reduced.
The current taxonomic consensus is that the use of subspecies and botanical variety within the ICBN scheme is confusing and not strictly necessary for cultivated Beta vulgaris. Single genes alone can determine swollen root shape and pigmentation, the different cultivated forms of Beta vulgaris have not been genetically or geographically isolated during their history, and there are no known barriers to gene exchange with the section Beta. The subspecies division for cultivated Beta vulgaris has been removed, although the different cultivated forms are still assigned to different varieties. Beta taxonomists, however, have suggested that it would be better, and less confusing, if all infraspecific classification for cultivated Beta vulgaris were done using the non-hierarchical horticultural classification system.
Infraspecific classification is frequently adopted for cultivated plants, because artificial selection results in clear morphological differences within a species. However, binomial nomenclature has a number of shortcomings when it comes to classifying cultivated plants below the species level. The system of horticultural classification, which uses the concepts of cultivated variety (cv. or var.) and cultivar race or group (cv. Group), has emerged as the most useful method of infraspecific classification for cultivated plants. The International Code of Nomenclature for Cultivated Plants (ICNCP), published in 1980, gives the accepted rules for applying this horticultural classification scheme.
The horticultural scheme has been erected for different reasons to those underlying the Linnaean system of binomial nomenclature. Rather than being a framework in which to catalogue all living creatures, the horticultural system of classification has more practical aims, for example, to achieve uniformity for seed registration and to form a basis for Plant Breeders' Rights legislation. Hierarchical taxonomic classification is often too rigid for people who work with cultivated plants. The horticultural system is flexible system and aids communication, enabling the transfer of clear and easily understood information between people working with cultivated plants.
The concept of cultivar is central to the ICNCP system. A cultivar is defined within the ICNCP as an assemblage of cultivated plants that is clearly distinguished by any characteristics (e.g. morphological or chemical), which when reproduced by sexual or asexual means retains these distinguishing characteristics. A cultivar can be a clone, line or assemblage of cross-fertilizing plants. Landraces or crop lines maintained by traditional agricultural methods, often in areas of crop origin and centres of genetic diversity, can be considered cultivars. Therefore, the ICNCP is a much more open and flexible system than the ICBN system, which is a closed classification system with rigid rankings. The ICNCP is considered subordinate to the ICBN, although both codes can be effectively co-ordinated in most cases.
The cultivar name of Beta vulgaris is usually given after the species or subspecies name, which for all cultivated beets is now Beta vulgaris subsp. vulgaris. Beetroot cultivars include, for example, Beta vulgaris subsp. vulgaris cv. Boltardy and Beta vulgaris subsp. vulgaris Red Ace F1. Sometimes, cultivar is given after the variety name, for example, Beta vulgaris var. conditiva Cheltenham Green Top. However, cultivar names do not overlap for the different cultivated forms of Beta vulgaris.
Variety is often used synonymously with cultivar, but the terms have distinct meanings. A cultivar is a plant that has been developed and maintained by cultivation as a result of agricultural or horticultural practices. The term cultivar is derived from cultivated variety. In binomial nomenclature, botanical variety is a fixed rank below subspecies. Cultivar is a category without rank, as long as it comes below the taxonomic rank to which it is assigned. Therefore, it may appear, for instance, below the rank of genus, species, subspecies or variety. In addition, cultivars are man-made, while there is no indication of whether a botanical variety exists naturally or needs to be maintained by artificial selection.
Within the ICNCP system, assemblages of similar cultivars can be grouped. The Leaf Beet cultivar grouping, Beta vulgaris subsp. vulgaris Leaf Beet Group, sometimes known as the Cicla grouping, contains Spinach Beet (perpetual spinach) and the chards.
Beetroot, forage beet and sugar beet are part of the Crassa cultivar grouping. Within the Crassa grouping, beetroot, forage beet and sugar beet are Beta vulgaris subsp. vulgaris Garden Beet Group, Beta vulgaris subsp. vulgaris Fodder Beet Group, and Beta vulgaris subsp. vulgaris Sugar Beet Group, respectively.
In addition to this system, beetroot cultivars are often further grouped with respect to root shape. Four categories of root shape are usually recognized: (i) globe or spherical, (ii) long, (iii) cylindrical or intermediate (half-long), and (iv) flat. The long and globe categories have sometimes been subdivided into classes. In one scheme, devised by Holland (1957) globe was subdivided into two classes, while long root shape was subdivided into five classes. However, the advantage of erecting subdivisions below the four basic root shapes is unclear. Today, most of the beetroot grown is globe-shaped.
Cultivated beets
Leaf beets are of two types, depending on whether or not a thick leaf midrib and petiole are present.
Leaf beets are known as salk in Arabic; tian cai in Chinese; bette or blette in French; mangold in German; bieta a foglia in Italian; acelga in Portuguese; svekla listovaja in Russian; and bleda or acelga in Spanish.
Spinach beet or perpetual spinach is grown for its leaves, which are used as greens or a potherb. It is distinct from spinach (Spinacia oleracea) and New Zealand spinach (Tetragonia expansa). Spinach beet does not have a thickened leaf midrib or a thickened petiole (leaf stem). It also lacks a swollen taproot. Spinach beet has never been bred intensively and there is no tradition of distinct cultivars. Three European varieties were proposed by Helm in 1957, based on foliage colour, but this classification has not persisted. Perpetual spinach is usually sold generically as 'spinach beet' or 'leaf beet'. However, the exception to the rule is the Italian cultivar of perpetual spinach called Erbette, which is listed in seed catalogues. Leaf beet has been consumed since ancient times throughout Europe. In parts of Ireland, where it is known as 'wild spinach', it has also been revered as a cure for sick sheep. Outside of Europe, spinach beet is an important crop in Northern India and parts of Central and South America.
Chards are grown for their foliage and in particular their thickened leaf midribs and petioles. As with spinach beet, there is no swollen taproot. Although some leaf beets have fairly thick roots, they are never fleshy. The white root of chard has in times past been consumed medicinally, in the form of infusions, and very occasionally as food, for example, in times of hardship. Chard is often used synonymously with Swiss chard, but older chard varieties are sometimes considered to be distinct from Swiss chard. Several types of Swiss chard can be distinguished, based on petiole or leaf midrib colour and other characteristics. Swiss Chard is sometimes also called seakale beet or silver beet. Lucullus is one of the oldest chard varieties and it has green leaf blades and white petioles. Chards occur in many colourful forms, including Bright Yellow Chard and Ruby or Rhubarb Chard. A popular recent introduction is Bright Lights Swiss Chard, an improved chard that has leaf midribs and petioles that occur in a mix of colours.
Spinach beet and Chard are highly perishable and do not transport well. Leaf beets are therefore rarely found in supermarkets in the USA and Western Europe. However, leaf beets are a popular vegetable grown for local consumption. They are particularly valued in warmer temperate regions, such as the south of France, where the summer weather can be too hot to grow other green leafy vegetables.
Beetroot has been primarily selected as a root vegetable, although its leaves are edible. Larger cultivars are grown as a staple root crop for winter sustenance, while smaller globe-shaped cultivars are grown as a summer salad crop.
Beetroot is called beet in North America. It is also referred to as garden beet, table beet or red beet in English; remolacha (or betarraga) hortelena, remolacha mesa or remolacha roja in Spanish; and beterraba hortela, beterraba de mesa or beterraba vermelha in Portuguese. Beetroot is called betterave, betterave rouge or betterave potage in French; rote Rote Beete or Runkelr German; Barbabietola in Italian; and rode biet or kroot in Dutch. It is silig in Arabic; gen tian cai in Chinese; and svekla stolovaja in Russian.
There are numerous cultivated varieties or cultivars of beetroot. These are listed and described further in Chapter Eight.
The leaves and roots of fodder or forage beet are fed to livestock and other animals, either fresh or as silage. They have large swollen roots that are classified in terms of their shape. Four basic root shapes are recognized: (i) flat globe, (ii) cylinder, (iii) globe and (iv) spindle. The taproots of flat globe and cylinder sit mainly above the soil level, while globe and spindle have storage roots sitting roughly half in and half out of the soil. In comparison, most beetroot cultivars have taproots that lie mainly below the soil level. In the past, different botanical varieties of fodder beet have been described based on their root colour: scarlet, pink, orange, yellow and white. The scarlet and pinks forms, however, are indistinguishable from large long-rooted beetroot. Modern forage beet cultivars can be distinguished from beetroot because of their white and zoned roots, their greater size, and their coarser root quality. Overall, the Fodder Beet Group comprises a large number of cultivars, displaying a wide range of variation in root shape and colour.
Mangel is an old variety that can be classified as distinct from modern fodder beets. Mangel is a heavier plants that stick out of the ground to a greater extent than improved fodder beet. Mangel originated from a cross between a beetroot and a leaf beet, while modern fodder beets result from a cross between mangel and sugar beet. The cylindrical-shaped variety Eckendorfer was developed around 1840 by plant breeders. Many of today's fodder beet cultivars are descended from it. Modern fodder beet roots contain around 3-5% sugar and 6-8% protein by dry weight.
The feeding of beet to animals has contributed to beetroot being unpopular or unfashionable as a food at certain times in parts of Europe. This may partly be due to etymology. The cultivated form of Beta vulgaris called mangel wurzel was originally known as mangold wurzel (root of the beet). Mangolt was the old German word for Beta vulgaris in general. However, this was corrupted among German speakers to mangel-wurzel (root of scarcity). Mangel wurzel became the name for fodder beets. The English translation of the title of Abbe Commerell's book, for instance, was Culture and Use of the Mangel Wurzel, a Root of Scarcity. The notion that beets are only to be consumed in times of hardship or fed to animals has persisted in some areas until relatively recently.
Sugar beet is the most recent of the cultivated beet crops and the most important in commercial terms. The conical swollen roots lack pigmentation and have a characteristically high sugar content. Sugar beet cultivars have been classified according to their root size and sugar content. There is much less variation in the Sugar Beet Group than in other beet cultivar groups.
Up until the 1870s, the focus was on breeding sugar beet to yield as much sugar as possible. However, after this time the aims of breeders diverged. This resulted in three groupings of sugar beet cultivars. Z-type (zucker-type) cultivars have small roots and high sucrose levels, E-type (ertrag-type) cultivars have large roots but lower sucrose levels, and N-type (normal-type) cultivars have medium-sized roots and intermediate sucrose content. The high sugar Z-types were a continuation of the continuous selection programmes for increasing the sugar levels in roots (as a percentage of root fresh weight). However, it was found that these types had a limited root yield potential. E-types were therefore selected for larger root size and higher root yield. The so-called normal types were the result of balancing both objectives. The classification of all sugar beet cultivars into Z, E and N-types has only recently been discontinued.
Sugar beet has whitish conical roots, up to half a metre in length. Modern sugar beet breeding programmes have produced a range of high-yielding and disease-resistant cultivars. The sweet beet in Marggraf's time contained up to 6% sucrose, whereas modern sugar beet cultivars contain around 18% sucrose. Modern beetroot cultivars, in comparison, typically contain between 6% and 10% sucrose.
Cultivated beet seed is botanically a fruit. Each knobbly 'seed' is a cluster of dried fruit. One to six fruit stick together to form a compressed corky structure called a glomerule or seedball. Seedballs are around 3-7 mm in diameter, depending on cultivar. Each fruit contains one seed or embryo, enclosed within its swollen cork-like base. The cork layer contains phenolic compounds that act to inhibit germination. Beetroot cultivars typically have glomerules containing around three true seeds. The true seeds are kidney-shaped, brown to black, and around 1.4 mm in diameter and 1.5 mm thick.
The glomerules or seedballs are said to be multigerm when they contain more than one seed. More than one seed can therefore germinate from each multigerm seedball. However, a number of modern beetroot cultivars and all modern sugar beet cultivars have been bred to be monogerm, with only one viable seed per seedball. This is beneficial for cultivation because less thinning is needed at the seedling stage. For mechanical planting of multigerm beetroot, the seedball is sometimes crushed into uniform pieces to separate out the seeds. Beet seed maintains its viability for around five years.
The search for monogerm beet seed started in around 1900. However, success was not achieved until the 1930s, when V.F. Savitsky (1902-1965) and co-workers identified monogerm sugar beet plants growing at the Sugar Beet Institute in Kiev. After the Second World War, Savitsky emigrated to the USA, where he identified five monogerm plants in a sugar beet seed field in Michigan in 1948. His work led to the development of commercial monogerm cultivars. By the 1960s, practically all sugar beet farmers in the USA and Western Europe were growing monogerm cultivars.
Monogerm sugar beet seed is coated into a pellet, which may contain fungicide or other pesticides, into a uniform shape that aids sowing using precision drills. The improved germination rates of modern monogerm seed enable it to be sown individually, into a final stand, without the need for thinning.
The tops, foliage or leaves of Beta vulgaris subsp. vulgaris grow in a basal rosette pattern. They emerge from the crown of the hypocotyl in an alternate formation. New leaves grow interior to older leaves. The leaves typically have a roughly triangular shape. They have strong long petioles or leaf stalks that broaden towards the base. The leaves can be dark or light green, or a dark red, depending on cultivated form and cultivar, and have a shiny surface.
The leaf surface is covered with an amorphous wax film. An analysis of compounds obtained by steam-distillation of Beta vulgaris leaves revealed a group of chemicals called n-alkanes. An alkane, in the terminology of organic chemistry, is a saturated hydrocarbon that has its carbon atoms attached in a continuous or branched chain; ethane, pentane, propane and isobutane are among the large family of alkane molecules. Other plants in the family Chenopodiaceae have similar combinations of n-alkanes to those identified from Beta vulgaris.
In a study conducted by Röttger it was found that alkanes identical to those found in the wax layer of Beta vulgaris leaves caused the beet fly (Pegomya betae) to lay eggs (oviposit) on an artificial surface that was normally ignored. The beet fly has co-evolved with Beta vulgaris to the extent it is now a specialist on this species, and uses the distinct chemical profile of its leaves as an oviposition stimulant. If a pregnant female fly senses their presence after landing on a plant, she is likely to lay eggs; but if she does not, she will fly to another plant.
The storage organ of beetroot, fodder beet and sugar beet is usually called a root. This is common usage and, for instance, has been used throughout this book. However, the swollen root of cultivated Beta vulgaris is technically made up from both the root and the hypocotyl, which is an enlarged region at the base of the stem. The hypocotyl is an intermediate region between stem and root and accounts for the top or crown part of the root. In sugar beet, the hypocotyl typically accounts for 10% of the storage organ, while 90% is root derived. However, this proportion varies and the amount derived from hypocotyl can be higher in fodder beet and beetroot, particularly in varieties that have crowns that extend above the soil surface.
Wild sea beet has little stem or root swelling and a long, stout, tapering main or taproot with a dense network of small side-roots. Leaf beets retain this basic tapering root form. In beetroot, the swollen storage root can be globular, cylindrical, flat or tapered, depending on the cultivated variety. The true taproot occurs below the hypocotyl. Lateral, side or adventitious roots, in two opposite rows on its lower part, grow from the true root. In loose soils, the rooting depth of beets can be up to 300 cm.
The roots of cultivated beet are either white or coloured. Chard and sugar beet have narrow and swollen white roots, respectively. Mangels and beetroot have roots that are typically yellow and red, respectively. Root colour is determined by the presence of pigments called betalains. These will be considered further in Chapter Five.
The hypocotyl and true root consist of alternating layers of conductive tissue and storage tissue. These are visible as distinct circles or cambium rings when the roots are cut transversely. Each ring is a vascular bundle comprising xylem, to the inside, and phloem, to the outside. The conductive tissue or xylem is typically broad and dark, and is involved in transporting water, sugar (sucrose) and nutrients around the plant. The storage tissue or phloem is typically narrow and light, and is where carbohydrates are transported and laid down during the first year's growth. In some beetroot cultivars, the colour difference between the darker-coloured bands of connective tissue and lighter-coloured bands of storage tissue can be subtle. In others, it can be highly pronounced. In Chioggia, for example, dark red bands alternate with almost white ones.
The girth of the root increases as additional cambium layers are added. In sugar beet at harvest, there are usually 12 to 15 rings. In harvested beetroot the number is usually less, because they are typically picked younger. Beetroot has been selected to have little lignin or hard fibrous tissue in its cambium layer. This makes the root's texture better for eating. Fodder beet and sugar beet, on the other hand, have been bred primarily for larger size and/or higher sugar content. In sugar beet, the concentration of sucrose is greatest in the very centre of the root.
Scientists are beginning to understand how different plant hormones interact during the formation of cambium layers in the roots of Beta vulgaris. These hormones produce different outcomes in the different cultivated forms of beet. It may be possible to increase levels of sugar storage in roots by manipulating plant hormones using biotechnological approaches.
Cultivated beet is a biennial plant. In the case of beetroot, fodder beet and sugar beet, foliage and an enlarged swollen storage root are produced during the first year's growth. In the second year of growth, resources stored in the root are diverted into producing a flower spike and seeds. When cultivated, these crops are biennials grown as annuals. However, to obtain seed, a second year's growth is usually required.
Beets have an inflorescence: literally a massing together of flowers. Flowering occurs at the end of the second year's growth, when a long single flower spike is produced. The flower spike occurs on the top of an elongated stem, which is usually around 50-150 cm high, although much higher flower spikes are possible. Flower spikes of 120 cm (4 feet) are typical of common beetroot cultivars. The spike grows upward and is branched (paniculate) at the top.
The inflorescence on the upper part of the flower spike has flowers irregularly arranged up its length. The flowers are greenish and sessile, being directly attached to the inflorescence with no individual stalks, either singly or more usually in groups or clusters of between two to five. The flowers are small and green or red in colour. As the inflorescence grows, adjoining flowers within a cluster cohere, eventually hardening to produce the uneven and wrinkled glomerules or seedballs.
Beta vulgaris flowers are bisexual or hermaphrodite, having both male and female reproductive organs. The stamen is the male part of the flower. Each flower has five stamens. An anther, from which pollen is released, tops each of the five stamens. The five stamens are fused at their bases to five petals and they surround the female part of the flower. This consists of a short pistil, topped by two to three stigmas, and a one-celled ovary embedded in a structure called a receptacle. The pollen released by the anthers is transported to the pistil. In the case of beetroot, the pollen is wind borne. When pollen lands on a stigma, a pollen tube starts to grow down through the pistil to the ovary, where fertilization takes place and seed is formed.
The seedballs turn brown on the flower spike, maturing from the base upwards. The seedballs do not readily drop and so the entire flower spike can be harvested when all the seeds are mature. Seedballs can be removed by pinching the stalks where they join the spike. The seed clusters should not be broken at this stage because this could injure the seeds.
Flowering is initiated in the second growing season after a prolonged period of cold weather (vernalisation), with temperatures below 10°F (50°F) for 30 to 60 days. Such conditions are typical in Northern Europe.
Cultivated Beta vulgaris that prematurely goes to seed at the end of its first growing season it is said to have "bolted". One of the most important factors in beet cultivation is to avoid sowing seed too early in the year, which can cause plants to bolt. Bolting can also be brought on by a sudden check on plant growth, such as that caused by cold weather, drought or insect pest attack. Bolting is very rare in perpetual spinach, which can therefore be harvested almost all year round, but it has in the past been a major problem in commercial sugar beet and beetroot cultivation.
One of the main aims of plant breeders has been to produce plants that are resistant to bolting, for early season planting. Workers at the Plant Breeding Institute in Cambridge, in England, first obtained bolting resistance in sugar beet in around 1940. Because temperature and day length are critical in determining bolting resistance, breeding work is carried out under the climatic conditions in which the beet is to be grown. The Cambridge team therefore also did breeding work in Scotland, and obtained lines that did not bolt under the demanding early season conditions there. These lines were used to produce commercial bolting-resistant cultivars. All modern sugar beet cultivars incorporate bolting resistance. Boltardy was one of the first bolting-resistant beetroot cultivars; it was introduced in the early 1960s. Many recent beetroot cultivars incorporate resistant to bolting. Bolting is therefore much less of a problem today than in the past.
Beets are outbreeding and cross-fertilize rather than self-fertilize. This makes it harder to obtain consistent lines for breeding. The incorporation of beneficial traits into beets was helped by the discovery of sugar beet plants with 'cytoplasmic male sterility', by F.V. Owen in the 1940s. F1 hybrids could subsequently be bred through controlled pollination and crossing of effectively inbred lines having male sterility. Most modern sugar beet and an increasing number of beetroot varieties are obtained in this way. F1 hybrids do not breed true and farmers need to obtain new seed each year, derived from further crossing of inbreeding lines. Hybrids have increased seedling vigour and enhanced resistance to pests and diseases. Later in this book we will see if beetroot F1 hybrids also taste as good as traditional varieties.



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July 2004 SFN.
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