Archive | March, 2016

Celebrating the history of peas and the International Year of the Pulse

This year (2016) has been designated the ‘International Year of Pulses’ (IYP) by the United Nations General Assembly. A quick look at the infographic on the official website tells you why: pulses are high in protein, their nutritional advantages include maintaining their quality after long storage, and they demand less water than other protein sources to produce, are economically accessible, and can also increase biodiversity and enhance soil fertility. Encouraging more pulses to be grown and eaten, and improving the protein content of the varieties under cultivation, is the goal of the international development and research communities, including the John Innes Centre. To mark this special year this blog delves a little into the history of just one of the pulses in widespread cultivation, the humble pea. Read what some of the early herbalists and botanists recorded about the pea (with illustrations from the John Innes Historical Collections). ‘Pulses’ are defined as edible dried mature seeds of leguminous crops so dried peas are the main focus of the blog, although the growth of the fresh pea market will also be touched on.

So to first briefly give some context, plant evidence points to two independent domestication events in peas. The first and largest cohort is Pisum sativum, which accounts for nearly all the cultivated peas worldwide.

Pisum sativum (syn. P. arvense) illustrated in John Sibthorpe's, Flora Graeca

Pisum sativum, which accounts for most of the cultivated peas worldwide, appears in many old botanical books as Pisum arvense (field peas). This illustration is from John Sibthorpe’s Flora Graeca (10 vols, London, 1806-40). John Innes Historical Collections.

The second domestication event took place in the Ethiopian highlands (‘Abyssinian peas’), a group that has proved difficult to classify. It is now classed as Pisum sativum sub-species abyssinicum, although molecular evidence shows it has more in common with two wild taxa, Pisum fulvum and Pisum elatius (P. sativum ssp elatius) than with sativum types. These peas had a more localised distribution in Africa.

Pisum fulvum illustrated in John Sibthorp's Flora Graeca

Pisum fulvum, one of the wild progenitors of Pisum abyssinicum. Illustration from John Sibthorp’s Flora Graeca (10 vols, London, 1806-40). John Innes Historical Collections.

Domesticated Pisum sativum, originated in the Near East around 8000 BCE, spread to Europe, Africa and Asia with Neolithic agriculture, fed Greek philosophers and Roman legionaries, and as ‘pease pottage’ (a gruel or thick soup), became a staple of medieval and early modern kitchens, keeping famine at bay.

Two illustrations of PIsum, from Ortus Sanitatis, 1511 and Hieronymus Bock, Kreuterbuch, 1560

Two early but unmistakable representations of Pisum from Ortus sanitatis, 1511 and from Hieronymus Bock, Kreuterbuch, 1560 (right). John Innes Historical Collections.

Pisum illustrated in Bock, Kreuterbuch, 1560

 

 

 

By the seventeenth century Pisum sativum had reached the Americas; peas are naturally packaged perfectly for expeditions, and the Pilgrim Fathers took dried peas with them on the Mayflower as part of their ration for the 65 day trip across the Atlantic. By this time European authors were beginning to discriminate between different pea varieties, and dividing ‘field’ from ‘garden’ peas.

17th century illustrations of peas, John Gerard's Herbal, 1597

Some of the different cultivated pea varieties available in the 17th century. Gerard noted that both field and garden peas were considered domesticated forms. John Gerard’s Herbal, 1597. John Innes Historical Collections.

 

Scottish or 'tufted' pea illustrated in John Gerard's Herbal, 1597

The Scottish or ‘tufted pea’ is a distinctive pea variety expressing apical fasciation. Heritage varieties of this form are still preserved in the Germplasm Resources Unit at the John Innes Centre today. Source: John Gerard, Herbal, 1597.

In the modern era, the creation and marketing of pea varieties proceeded apace with the development of plant breeding and the rise of horticultural companies like Suttons Seeds of Reading (founded 1806) or Carter’s Seeds of London (founded 1863). Today the John Innes Germplasm Resources Unit holds over 3,620 different ‘accessions’ of peas, from wild and domesticated peas collected on expeditions around the world, to ‘heritage’ peas from Great Britain (the oldest in the collection is the ‘Mummy Pea’ introduced in 1788), to an important collection of pea variants arising from mutations discovered or generated by scientists and breeders around the world. The development of new forms of peas in the 1970s by researchers at John Innes (the ‘leafless’ and ‘semi-leafless’ pea varieties), was based on mutant lines held in the collection. Today semi-leafless accounts for almost all dried pea varieties grown in the UK.

Eating peas fresh and green (rather than starting your dish with soaked dried peas) is a relatively modern luxury. Little dishes of garden peas were once presented for the enjoyment of Kings, Queens and Cardinals. By the time John Parkinson was writing his Paradisi in sole paradisus terrestris (2nd ed. 1656) green peas were eaten by rich and poor. He records that the ‘fairest’, sweetest, youngest and earliest peas were eaten by the rich, whereas the later, ‘meaner’ and lower priced peas were eaten by the poor or ‘serve to boyl into a kind of broth or pottage’ flavoured with Thyme, Mints, Savory ‘or some other such hot herbs to give it better relish’. Peas, he notes were especially consumed ‘in Town and Country in the Lent-time, especially of the poorer sort of people’. Mariners were another group relying on peas to sustain them ‘It is much used likewise at Sea for them that go on long voyages, and is for change, because it is fresh, a welcome diet to most persons therein’. As for the health benefits of including peas in the diet, 17th century authors rather sat on the fence, they were neither bad nor good!

Comments on the dietary value of peas from John Gerard's Herbal, 1636

Today peas are a taken-for-granted vegetable, and partly because food cultures have continued to evolve in the industrial age and new uses for peas have developed. Canned and frozen peas transformed the ‘fresh’ pea market. Dried peas found a new lease of life as ‘mushy peas’ (made from marrowfat peas). These will accompany your pie on a night out or at a football match in the north of England, and are also served alone as a snack in parts of the Midlands and North. A permanent stall in Norwich Market devoted to mushy peas has traded daily (except Sundays) since 1969. As an accompaniment to ‘traditional’ fish and chips mushy peas are an innovation of the 1970s. The dried pea remains central to many food cultures around the world including India, the Middle East, the Far East, Europe, and North and South America. Eating pea soup on Thursdays is a weekly tradition in Sweden and Finland and has been so ever since the Middle Ages. And in the Netherlands pea soup is traditionally served on New Year’s Day. Yet in the UK the pulse acreage in general has been in decline since 2001, falling from 319,000 hectares to 157,000 hectares in 2012. Combinable peas (for the dried pea market) have suffered the greatest decline, a 70% fall in the same period, though the acreage of vining (fresh) peas has been more stable it is also in gradual decline. The introduction of the three crop rule in 2015 as part of the Common Agricultural Policy reform (aimed at increasing diversification and ensuring that farming practices benefit the environment) has provided a significant stimulus to pulse growers but their expansion is still highly dependent on the size of the market and the commodity value.

The observation that peas and beans have root nodules (where nitrogen-fixing micro-organisms live in symbiosis with these plants) was made by plant anatomists in the seventeenth century. The role of legumes in restoring fertility to arable land was also well-known by the early nineteenth century, even if the nitrogen-fixing process itself remained largely a mystery. The famous ‘Norfolk four-course rotation’, popularised by the Holkham Estate in north Norfolk, was based on the clover crop for nitrogen fixing in a field rotation of wheat, barley, turnips and clover. In modern crop rotations peas take the place of clover as so few arable farms now have grazing livestock. Today’s CAP three-crop rule is a move to bring the benefits of pulses and their nitrogen fixation back onto more farms. To read more about the peas grown in the UK and their future prospects follow the link to the recent Anderson Report (2015) commissioned by JIC.

17th century illustration of root nodules on a pea plant, Malpighi, Anatome Plantarum, 1675

Root nodules can clearly be seen on the top left hand pea plant in this seventeenth century illustration. From Marcello Malpighi, Anatome plantarum (London, 1675). John Innes Historical Collections.

Given the number of byways a history of the pea could lead you down it’s surprising this crop hasn’t attracted more attention from historians (if you know of a good source for peas do let me know on Twitter @JIChistory or email sarah.wilmot@jic.ac.uk). I know of nothing to parallel Redcliffe Salaman’s The History and Social Influence of the Potato (1949) for example, or the delightful assemblage that is the virtual ‘World Carrot Museum’ founded and curated by John Stolarczyk from Skipton in North Yorkshire. A starting point might be Mike Ambrose’s 2008 chapter on the plant breeding history of the garden pea. In addition, and apparently well worth a visit, there are the Grade II listed ‘Pea Rooms’ at Heckington, Lincolnshire (post code NG34 9JH) where pea history is preserved in photos on the wall (if anyone has visited and has photos please get in touch). Peas also assume an important role, if still not quite centre stage, in the history of genetics, thanks to the focus on Gregor Mendel’s pea hybridisation experiments (published in 1866) and the attention paid them since their ‘rediscovery’ around 1900 (see earlier blogs for a flavour of the controversies around Mendel and his British defender, William Bateson, the first Director of the John Innes). The 2016 anniversary of Mendel’s publication will bring historians of science together for a new round of commemoration, new Mendel exhibitions, and some exciting new historical interpretations. The British Society for the History of Science (BSHS) is about to launch an educational initiative in partnership with the Brno Mendel Museum and the Royal Society to celebrate the contribution of Mendelian genetics to modern science and highlight the contributions made by Cambridge women scientists in the early twentieth century.

Caroline Pellew, one of the early pea geneticists at John Innes, illustrated by Dorothy Cayley.

Caroline Pellew working in the plots at the John Innes Horticultural Institution in the 1910s. Caroline was one of the Institute’s first pea geneticists, working alongside William Bateson. Bateson had encouraged women researchers to take up genetics both at Cambridge and at the John Innes. Caroline’s route into plant science was University College Reading’s two-year Diploma in Horticulture though, not the University of Cambridge. Illustration by Dorothy Cayley, John Innes Historical Collections.

The celebrations will coincide with the publication by the BSHS of a new edited English translation of Mendel’s work (surprisingly the one relied on currently is still the one commissioned by Bateson in the early 1900s), and will be followed up by educational web-based material. Meanwhile a helpful textbook edited by Denise Phillips and Sharon Kingsland, New Perspectives on the History of Life Sciences and Agriculture (Springer, 2015; available in the John Innes History of Genetics Library) includes chapters by Sanders Gliboff and Jonathan Harwood re-assessing the literature surrounding the ‘Mendelian revolution’ and looking again at Mendel’s impact on plant breeding (and its wider ramifications for debates about human breeding). At Leeds, Greg Radick is working on a biography (due out in 2018) of W F R Weldon, Bateson’s arch rival and critic of Mendelian genetics in Britain.  Provisionally titled Disputed Inheritance: The Battle over Mendelism and the Future of Biology, you can expect some challenging new insights on the controversy caused by Mendel’s peas. For a flavour of what’s to come listen to the Mendel discussion hosted by the Royal Society last summer.

 

 

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