Pea

• 1. Introduction

  ›

  The pea has fed civilisations for at least ten thousand years. Seeds showing domesticated characteristics have been unearthed at archaeological sites around what is now Turkey, and the crop's reach was already global long before anyone thought to write its name down. By the time vendors in the streets of Athens were selling hot pea soup, somewhere between 500 and 400 BC, this small legume had become woven into the fabric of daily life across the ancient world.

  What makes the pea remarkable is the sheer range of things it has been asked to do. It has staved off famine in medieval Europe and graced the table of Louis XIV. It gave an Austrian monk the raw material to crack the code of heredity. Its roots silently replenish the soil it grows in. And its name in English is itself a kind of accident, the product of a grammatical misunderstanding that unfolded over centuries.

  How did a humble flowering annual travel from the Mediterranean to the courts of Versailles? How did Gregor Mendel's garden in Austria change the course of science? And why, in a poll of two thousand people in 2005, did the British public rank the pea as their seventh favourite culinary vegetable? Those are the threads this documentary will follow.

• 2. A Name in Flux

  ›

  Carl Linnaeus assigned the pea its official scientific name, Pisum sativum, in 1753. The Latin phrase means, simply, cultivated pea. That clarity has not lasted unchallenged: some sources now treat the plant as Lathyrus oleraceus, though the need and justification for the change remain disputed.

  The common English word has its own tangled history. It traces back to the Latin pisum, itself a latinisation of the Greek word pison, meaning pea. English borrowed it not from Latin directly but through the noun pease, which was used as both singular and plural. Over time, speakers assumed that because pease ended in the letter s, it must be plural, and so they invented a new singular by dropping that final s. The result was pea. Linguists call this process back-formation, and the pea is one of its most cited examples.

  The word pease did not vanish entirely. It survives in pease pudding, the thick, savoury dish made from dried split peas that appears in British cookery still. The broader Fabaceae family contributes several other plants that share the pea's name without sharing its species: the pigeon pea, the cowpea, the seeds of several Lathyrus species, and Sturt's desert pea, Swainsona formosa, each carrying the name as a loose descriptor of edible, pod-borne seeds.

• 3. From Field to Royal Table

  ›

  In the Middle Ages, it was the field pea that mattered most. Charles the Good, count of Flanders, noted explicitly in 1124 that field peas were the staple keeping famine at bay. The field pea, sometimes called the Austrian winter pea or the dun pea for its grey-brown colouring, is one of the oldest domesticated crops on earth. Archaeological sites near present-day Turkey have yielded seeds with domesticated characteristics dating back at least seven thousand years.

  Fresh green peas were a different matter entirely. Eating peas while still immature and sweet was an innovation of early modern European cuisine, and for a time it was an extravagance. Snow peas and snap peas, eaten pod and all, were introduced to France from the market gardens of Holland during the reign of Henri IV, carried through the French ambassador.

  In January 1660, a hamper of green peas was brought from Genoa to the court of Louis XIV with some staged fanfare. They were shelled by the Savoyan comte de Soissons, who had married a niece of Cardinal Mazarin. Small dishes were then served to the King, the Queen, Cardinal Mazarin, and Monsieur, the king's brother. The peas were grown for earliness, warmed with manure and sheltered under glass, and remained a luxurious delicacy for decades. By 1696, both Mme de Maintenon and Mme de Sevigne were each reporting that fresh peas had become "a fashion, a fury."

  Across the Atlantic, the appetite for peas was equally serious. Thomas Jefferson grew more than thirty cultivars of peas on his estate.

• 4. Mendel's Garden

  ›

  In the mid-19th century, Gregor Mendel, an Austrian monk, chose peas for a reason that had nothing to do with their taste. He could grow them easily, pure-bred strains were readily available, and the structure of pea flowers naturally prevents cross-pollination while still allowing it when the experimenter wants it. Over the course of his experiments, Mendel grew and examined about twenty-eight thousand pea plants.

  He cross-bred tall plants with dwarf ones, green peas with yellow, purple flowers with white, wrinkled seeds with smooth ones, and several other paired traits. In every case, the first generation of offspring displayed only one of the two traits, the dominant one. When those plants were allowed to self-pollinate, their offspring showed the dominant trait in roughly a 3-to-1 ratio against the recessive trait. Mendel concluded that each parent contributed a separate "vote" to the offspring's appearance, and that a recessive trait would only show itself when it was inherited from both parents.

  He also established that different traits are inherited independently of one another. In doing so, Mendel had unwittingly resolved a problem that had troubled Charles Darwin: his theory of evolution could not explain how new, beneficial traits survived in a population rather than blending back into the average over generations. Darwin himself had no answer to this. Mendel's findings provided one, but his work was published in an obscure Austrian journal and was not rediscovered by the wider scientific community until around 1900.

• 5. The Living Soil

  ›

  Beneath the surface of a pea plant, something else is at work. Peas, like other legumes, host symbiotic bacteria called Rhizobia inside nodules on their roots. These bacteria fix atmospheric nitrogen, converting it from its molecular form into ammonia, and then into ammonium, a form that plants can absorb and use to build amino acids and proteins.

  When the pea plant dies after harvest, all the nitrogen stored in its remaining tissues is released back into the soil. There it converts into nitrate, which becomes available as fertiliser for the next crop grown in that ground. This quality helps explain why peas have been included in crop rotations for millennia: their roots leave the soil richer than they found it.

  The pea leaf weevil, Sitona lineatus, attacks precisely this strength. Native to Europe but now found in places as far away as Alberta, Canada, the weevil larva feeds on the root nodules themselves, cutting off the plant's nitrogen supply and stunting leaf and stem growth. Adult weevils leave the plant's leaves with a distinctive notched, c-shaped bite pattern. The pea moth adds a different threat: its caterpillars resemble small white maggots inside the pods and consume the developing peas directly. Before modern insecticides, those caterpillars were a common sight in harvested pods.

• 6. Varieties and the Genome

  ›

  Garden peas alone encompass a wide range of cultivars. Some, like Alaska and Tom Thumb, mature in fifty-five days. Others, like the heirloom variety Tall Telephone, take seventy-five days and can climb to roughly two metres with support. Vining cultivars grow thin tendrils that coil around any available structure, and the traditional method of providing that structure is to push pruned woody branches upright into the soil. These are called pea sticks, or sometimes pea brush.

  Snow peas and snap peas belong to a cultivar group, the Macrocarpon Group, based on the variety Pisum sativum var. macrocarpum, which was first named in 1825. The original description noted the very compressed, non-leathery, edible pods. Snow peas have flat pods and thin walls; snap peas have rounded pods with thicker walls. Both are generally still picked by hand, though a prototype for an automated snap pea harvester was being researched as recently as 2017.

  Sequencing the pea genome proved far harder than for other legumes. Its size of 4.45 gigabases made it difficult to work with compared to plants like Medicago truncatula or soybeans. The International Pea Genome Sequencing Consortium was formed to address this, and in September 2019 the group announced a draft assembly covering 88 percent of the genome. That assembly, built around the inbred French cultivar Caméor, predicted 44,791 gene-coding sequences. A pea pangenome followed in 2022.

• 7. A Global Pantry

  ›

  In 2023, world production of green peas reached 21.5 million tonnes. China and India together accounted for 86 percent of that total. Russia and China lead field pea production as well, followed by Canada, Europe, Australia, and the United States, which together cultivate over 1.8 million hectares and are major exporters.

  The ways peas are eaten span an extraordinary range of cuisines. In Japan, China, Taiwan, and parts of Southeast Asia including Thailand, the Philippines, and Malaysia, peas are roasted and salted and served as snacks. In Hungary and Serbia, pea soup arrives with dumplings and hot paprika. In Greece, Tunisia, Turkey, and Cyprus, peas go into a stew with lamb and potatoes. In India, fresh peas appear in aloo matar, curried with potatoes, and in mattar paneer, cooked with paneer cheese. In Guyana and Trinidad, split peas are used to make dal.

  In the United Kingdom, mushy peas, made from dried, rehydrated, and mashed marrowfat peas, have moved from their origins in northern England to become a nationwide staple, especially alongside fish and chips. The first sweet-tasting pea was developed in the 18th century by Thomas Edward Knight, an amateur plant breeder from Downton, near Salisbury. Modern split peas, with their indigestible skins rubbed off, became available only in the later 19th century. The first pea viner machine capable of shelling peas through impact was invented around 1890 by John Alexander Chisholm, a development that made large-scale commercial harvesting possible and helped carry the pea from royal courts and manor gardens into the kitchens of ordinary households around the world.