Pea

Pea(pisuminLatin) is apulse, vegetable or fodder crop, but the word often refers to theseedor sometimes thepodof thisflowering plantspecies. Each pod contains several seeds (peas), which can have green or yellow cotyledons when mature. Botanically, pea pods arefruit,since they contain seeds and develop from the ovary of a (pea) flower. The species namePisum sativumis also used to describe other edible seeds from theFabaceaefamily such as thepigeon pea(Cajanus cajan), thecowpea(Vigna unguiculata), the seeds from several species ofLathyrusand is used as a compound form for exampleSturt's desert pea.
Peas areannual plants, with alife cycleof one year. They are a cool-season crop grown in many parts of the world; planting can take place from winter to early summer depending on location. The average pea weighs between 0.1 and 0.36 grams (0.004–0.013 oz).The immature peas (and insnow peasandsnap peasthe tender pod as well) are used as a vegetable, fresh, frozen or canned; varieties of the species typically called field peas are grown to produce dry peas like thesplit peashelled from a matured pod. These are the basis ofpease porridgeandpea soup, staples ofmedieval cuisine; in Europe, consuming fresh immature green peas was an innovation ofearly modern cuisine.
A pea is a most commonly green, occasionally golden yellow,or infrequently purplepod-shapedvegetable, widely grown as a cool-season vegetable crop. The seeds may be planted as soon as the soil temperature reaches 10 °C (50 °F), with the plants growing best at temperatures of 13 to 18 °C (55 to 64 °F). They do not thrive in the summer heat of warmer temperate and lowland tropicalclimates, but do grow well in cooler, high-elevation, tropical areas. Many cultivars reach maturity about 60 days after planting.
Peas have both low-growing andviningcultivars. The vining cultivars grow thintendrilsfrom leaves that coil around any available support and can climb to be 1 to 2 metres (3 to 7 ft) high. A traditional approach to supporting climbing peas is to thrust branches pruned fromtreesor other woody plants upright into the soil, providing a lattice for the peas to climb. Branches used in this fashion are calledpea sticksor sometimespea brush. Metal fences,twine, or netting supported by a frame are used for the same purpose. In dense plantings, peas give each other some measure of mutual support. Pea plants canself-pollinate.
The peakaryotypeconsists of sevenchromosomes, five of which areacrocentricand twosubmetacentric.Despite its scientific popularity, its relatively large genome size (4.45Gb) made it challenging to sequence compared to other legumes such asMedicago truncatulaandsoybeans. The International Pea Genome Sequencing Consortium was formed to develop the first peareference genome, and the draft assembly was officially announced in September 2019. It covers 88% of the genome (3.92Gb) and predicted 44,791 gene-coding sequences. The pea used for the assembly was the inbred French cultivar "Caméor".
Carl Linnaeusgave the species the scientific namePisum sativumin 1753 (meaningcultivatedpea). Some sources now treat it asLathyrus oleraceus,although the need and justification for this change is disputed.
The termpeaoriginates from theLatinwordpisum,which is thelatinisationof theGreekπίσον(pison), neuter variant form ofπίσος(pisos) 'pea'.It was adopted intoEnglishas thenounpease(pluralpeasen), as inpease pudding. However, by analogy with other plurals ending in-s, speakers began construingpeaseas apluraland constructing the singular form by dropping the-s, giving the termpea. This process is known asback-formation.
There are many varieties (cultivars) of garden peas. Some of the most common varieties are listed here.PMRindicates some degree ofpowdery mildewresistance;afilatypes, also called semi-leafless, have clusters of tendrils instead of leaves.Unless otherwise noted these are so called dwarf varieties which grow to an average height of about 1m.  Giving the vines support is recommended, but not required.  Extra dwarf are suitable for container growing, reaching only about 25 cm.  Tall varieties grow to about 2m with support required.
Some peas lack the tough membrane inside the pod wall and have tender edible pods.There are two main types:
The namesugar peacan include both typesor be synonymous with either snow peas or snap peas in different dictionaries.Likewisemangetout(/ˈmɒ̃ʒˌtuː/; fromFrench:pois mange-tout, 'eat-all pea').
Snow peas and snap peas both belong to Macrocarpon Group,acultivar groupbased on the varietyPisum sativumvar.macrocarpumSer.named in 1825.It was described as having very compressed non-leathery edible pods in the original publication.
Thescientific namePisum sativumvar.saccharatumSer.is often misused for snow peas. The variety under this name was described as having sub-leathery and compressed-teretepods and a French name ofpetit pois.The description is inconsistent with the appearance of snow peas, and therefore botanists have replaced this name withPisum sativumvar.macrocarpum.
Thefield peais a type of pea sometimes calledP. sativumsubsp.arvense(L.) Asch.  It is also known as dun (grey-brown) pea, Kapucijner pea, or Austrian winter pea, and is one of the oldest domesticated crops, cultivated for at least 7,000 years.  Field peas are now grown in many countries for both human consumption and stockfeed.  There are several cultivars and colors including blue, dun (brown), maple and white. This pea should not be confused with thecowpea(Vigna unguiculata) which is sometimes called the "field pea" in warmer climates.
It is a climbing annual legume with weak, viny, and relatively succulent stems. Vines often are 4 to 5 feet (120 to 150 cm) long, but when grown alone, field pea's weak stems prevent it from growing more than 1.5 to 2 feet (45 to 60 cm) tall. Leaves have two leaflets and a tendril. Flowers are white, pink, or purple. Pods carry seeds that are large (4,000 seeds/lb), nearly spherical, and white, gray, green, or brown. The root system is relatively shallow and small, but well nodulated.
The field pea is a cool-season legume crop that is grown on over 25 million acres worldwide. It has been an importantgrain legumecrop for millennia, seeds showing domesticated characteristics dating from at least 7,000 years ago have been found in archaeological sites around what is nowTurkey.  Field peas or "dry peas" are marketed as a dry, shelled product for either human orlivestockfood, unlike the garden pea, which is marketed as a fresh or canned vegetable. The major producing countries of field peas are Russia and China, followed by Canada, Europe, Australia and the United States. Europe, Australia, Canada and the U.S. raise over 4.5 million acres (18,000 km²) and are major exporters of peas. In 2002, there were approximately 300,000 acres (1,200 km²) of field peas grown in the U.S.
The wild pea is restricted to theMediterranean Basinand the Near East. The earliest archaeological finds of peas date from the lateNeolithicera of current Syria, Anatolia, Israel, Iraq, Jordan and Greece. In Egypt, early finds date fromc.4800–4400 BC in theNile deltaarea, and from c. 3800–3600 BC in Upper Egypt. The pea was also present inGeorgiain the 5th millennium BC. Farther east, the finds are younger. Peas were present inAfghanistanc. 2000 BC, inHarappan civilizationaround modern-dayPakistanand western- and northwesternIndiain 2250–1750 BC. In the second half of the 2nd millennium BC, thislegume cropappears in theGanges Basinand southern India.
In early times, peas were grown mostly for their dry seeds.From plants growing wild in the Mediterranean Basin, constant selection since theNeolithic dawn of agricultureimproved their yield. In the early 3rd century BC,Theophrastusmentions peas among thelegumesthat are sown late in the winter because of their tenderness.In the first century AD,Columellamentions them inDe re rustica, when Roman legionaries still gathered wild peas from the sandy soils ofNumidiaandJudeato supplement their rations.
In theMiddle Ages, field peas are constantly mentioned, as they were the staple that keptfamineat bay, asCharles the Good, count ofFlanders, noted explicitly in 1124.
Green "garden" peas, eaten immature and fresh, were an innovative luxury ofEarly Modern Europe. In England, the distinction betweenfield peasandgarden peasdates from the early 17th century:John GerardandJohn Parkinsonboth mention garden peas.Snow and snap peas, which the French calledmange-tout, because they were eaten pods and all, were introduced to France from the market gardens ofHollandin the time ofHenri IV, through the French ambassador. Green peas were introduced fromGenoato the court ofLouis XIV of Francein January 1660, with some staged fanfare. Ahamperof them was presented before the King. They were shelled bythe Savoyan comte de Soissons, who had married a niece ofCardinal Mazarin. Little dishes of peas were then presented to the King, the Queen, Cardinal Mazarin and Monsieur, the king's brother.Immediately established and grown for earliness warmed withmanureand protectedunder glass, they were still a luxurious delicacy in 1696, whenMme de MaintenonandMme de Sevignéeach reported that they were "a fashion, a fury".
The firstsweet tasting peawas developed in the 18th century by amateur plant breeder Thomas Edward Knight of Downton, near Salisbury, England.
Modernsplit peas, with their indigestible skins rubbed off, are a development of the later 19th century.
The top producer of green peas is China with 12.2 million tons, followed by India (4.8 million tons), the U.S. (0.31 million tons), France (0.23 million tons) and Egypt (0.15 million tons). The United Kingdom, Pakistan, Algeria, Peru and Turkey complete the top 10.
Pea grading involves sorting peas by size, in which the smallest peas are graded as the highest quality for their tenderness.Brines may be used, in which peas are floated, from which their density can be determined.
A variety of diseases affect peas through a number ofpathogens, including insects, viruses, bacteria and fungi.In particular, virus disease of peas has worldwide economic importance.
Additionally, insects such as the pea leaf weevil (Sitona lineatus) can damage peas and other pod fruits. The pea leaf weevil is native to Europe, but has spread to other places such asAlberta, Canada. They are about 3.5 millimetres (0.14 in)—5.5 millimetres (0.22 in) long and are distinguishable by three light-coloured stripes running length-wise down thethorax. The weevillarvaefeed on theroot nodulesof pea plants, which are essential to the plants' supply ofnitrogen, and thus diminish leaf and stem growth. Adult weevils feed on the leaves and create a notched, "c-shaped" appearance on the outside of the leaves.
Thepea mothcan be a serious pest producing caterpillars the resemble small white maggots in the pea-pods. The caterpillars eat the developing peas making them unsightly and unsuitable for culinary use.Prior to the use of modern insecticides, pea moth caterpillars were a very common sight in pea pods.
Some people experienceallergic reactionsto peas, as well aslentils, withvicilinor convicilin as the most common allergens.
Favism, orFava-bean-ism, is agenetic deficiencyof the enzyme glucose-6-phosphate dehydrogenase that affectsJews, other Middle Eastern Semitic peoples, and other descendants of the Mediterranean coastal regions. In this condition, the toxic reaction to eating most, if not all,beansishemolytic anemia, and in severe cases, the released circulating free hemoglobin causesacute kidney injury.
Raw green peas are 79% water, 14%carbohydrates, 5%protein, and contain negligiblefat. In a reference amount of100 grams (3+1⁄2ounces), raw green peas supply 339 kilojoules (81 kilocalories) offood energy, and are a rich source (20% or more of theDaily Value, DV) ofvitamin C(48% DV),vitamin K,thiamine, andmanganese, with severalB vitaminsanddietary mineralsin moderate amounts (11–16% DV).
In modern times peas are usually boiled orsteamed, which breaks down the cell walls and makes them taste sweeter and the nutrients morebioavailable. Along withbroad beansandlentils, these formed an important part of the diet of most people in the Middle East, North Africa and Europe during theMiddle Ages.By the 17th and 18th centuries, it had become popular to eat peas "green", that is, while they are immature and right after they are picked.New cultivars of peas were developed by the English during this time, which became known as "garden" or "English" peas. The popularity of green peas spread toNorth America.Thomas Jeffersongrew more than 30 cultivars of peas on his estate.With the invention of canning, peas were one of the first vegetables to be canned.
Fresh peas are often eaten boiled and flavored withbutterand/orspearmintas a side dish vegetable. Salt and pepper are also commonly added to peas when served. Fresh peas are also used inpot pies, salads andcasseroles. Pod peas (snow peasandsnap peas) are used in stir-fried dishes, particularly those inAmerican Chinese cuisine.Pea pods do not keep well once picked, and if not used quickly, are best preserved by drying,canningorfreezingwithin a few hours of harvest.
InIndia, fresh peas are used in various dishes such asaloo matar(curried potatoes with peas) ormattar paneer(paneercheese with peas), though they can be substituted with frozen peas as well. Peas are also eaten raw, as they are sweet when fresh off the bush. Green peas known as hasiru batani inKannadaare used to make curry and gasi.Split peas are also used to makedal, particularly inGuyana, andTrinidad, where there is a significant population ofIndians.
Dried peas are often made into asoupor simply eaten on their own. InJapan,China,Taiwanand someSoutheast Asiancountries, includingThailand, thePhilippinesandMalaysia, peas are roasted and salted, and eaten assnacks. In the Philippines, peas, while still in their pods, are a common ingredient in viands andpansit. In the UK, dried yellow or green split peas are used to makepease pudding(or "pease porridge"), a traditional dish. In North America, a similarly traditional dish is splitpea soup.
Pea soup is eaten in many other parts of the world, includingnorthern Europe, parts ofmiddle Europe,Russia,Iran,IraqandIndia.
InChinese cuisine, the tender new growth [leaves and stem]dou miao(豆苗;dòu miáo) are commonly used in stir-fries. Much like picking the leaves for tea, the farmers pick the tips off of the pea plant.
InGreece,Tunisia,Turkey,Cyprus, and other parts of the Mediterranean, peas are made into a stew with lamb and potatoes.
InHungaryandSerbia, pea soup is often served withdumplingsand spiced with hotpaprika.
In the United Kingdom, dried, rehydrated and mashedmarrowfat peas, or cooked green split peas, known asmushy peas, are popular, originally in the north of England, but now ubiquitously, and especially as an accompaniment tofish and chipsormeat pies, particularly infish and chip shops.Sodium bicarbonateis sometimes added to soften the peas. In 2005, a poll of 2,000 people revealed the pea to be Britain's seventh favourite culinary vegetable.
Processed peas are mature peas which have been dried, soaked and then heat treated (processed) to prevent spoilage—in the same manner aspasteurizing. Cooked peas are sometimes sold dried and coated withwasabi,salt, or other spices.
In North Americapea milkis produced and sold as an alternative tocow milkfor a variety of reasons.
In East Asia, pea sprouts or shoots (豆苗;완두순)were once dedicated cuisinewhen the plant was less highly available. Today, when the plant can be easily grown, fresh pea shoots are available in supermarkets or may be grown at home.
In order to freeze and preserve peas, they must first be grown, picked, and shelled. Usually, the more tender the peas are, the more likely that they will be used in the final product. The peas must be put through the process of freezing shortly after being picked so that they do not spoil too soon. Once the peas have been selected, they are placed in ice water and allowed to cool. After, they are sprayed with water to remove any residual dirt or dust that may remain on them. The next step isblanching. The peas are boiled for a few minutes to remove any enzymes that may shorten their shelf life. They are then cooled and removed from the water. The final step is the actual freezing to produce the final product.This step may vary considerably; some companies freeze their peas by air blast freezing, where the vegetables are put through a tunnel at high speeds and frozen by cold air. Finally, the peas are packaged and shipped out for retail sale.
In the mid-19th century, Austrian monkGregor Mendel's observations of pea pods led to the principles ofMendelian genetics, the foundation of moderngenetics.He ended up growing and examining about 28,000 pea plants in the course of his experiments.
Mendel chose peas for his experiments because he could grow them easily, pure-bred strains were readily available,and the structure of the flowers protect them from cross-pollination, and cross pollination was easy.Mendel cross-bred tall and dwarf pea plants, green andyellow peas, purple and white flowers, wrinkled and smooth peas, and a few other traits. He then observed the resulting offspring. In each of these cases, one trait is dominant and all the offspring, or Filial-1 (abbreviated F1) generation, showed the dominant trait. Then he allowed the F1generation to self pollinate and observed their offspring, the Filial-2 (abbreviated F2)  generation. The F2plants had the dominant trait in approximately a 3:1 ratio. He studied later generations of self pollinated plants, and performed crosses to determine the nature of the pollen and egg cells.
Mendel reasoned that each parent had a 'vote' in the appearance of the offspring, and the non-dominant, orrecessive, trait appeared only when it was inherited from both parents. He did further experiments that showed each trait is separately inherited. Unwittingly, Mendel had solved a major problem withCharles Darwin'stheory of evolution: how new traits were preserved and not blended back into the population, a question Darwin himself did not answer. Mendel's work was published in an obscure Austrian journal and was not rediscovered until about 1900.
Peas, like many legumes, containsymbioticbacteria calledRhizobiawithinroot nodulesof theirroot systems. These bacteria have the special ability tofix nitrogenfrom atmospheric, molecular nitrogen (N2) intoammonia(NH3).The chemical reaction is:
Ammonia is then converted to another form,ammonium(NH+4), usable by (some) plants by the following reaction:
The root nodules of peas and other legumes are sources of nitrogen that they can use to makeamino acids, constituents of proteins. Hence, legumes are good sources ofplant protein.
When a pea plant dies in the field, for example following theharvest, all of its remaining nitrogen, incorporated intoamino acidsinside the remaining plant parts, is released back into thesoil. In the soil, the amino acids are converted to nitrate (NO−3), that is available to other plants, thereby serving as fertilizer for future crops.
Peashootersare a kind of toy in which peas serve as a projectile.
A pea plays an important role inHans Christian Andersen's 19th-century fairy taleThe Princess and the Pea.