A pea is most commonly the small spherical seed or the seed-pod of the pod fruit Pisum sativum.^[1] Each pod contains several peas. Peapods are botanically a fruit,^[2] since they contain seeds developed from the ovary of a (pea) flower. However, peas are considered to be a vegetable in cooking. The name is also used to describe other edible seeds from the Fabaceae such as the pigeon pea (Cajanus cajan), the cowpea (Vigna unguiculata), and the seeds from several species of Lathyrus.

P. sativum is an annual plant, with a life cycle of one year. It is 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.^[3] The species is used as a vegetable, fresh, frozen or canned, and is also grown to produce dry peas like the split pea. These varieties are typically called field peas.

The wild pea is restricted to the Mediterranean basin and the Near East. The earliest archaeological finds of peas come from Neolithic Syria, Turkey and Jordan. In Egypt, early finds date from ca. 4800–4400 BC in the Nile delta area, and from ca. 3800–3600 BC in Upper Egypt. The pea was also present in Georgia in the 5th millennium BC. Farther east, the finds are younger. Peas were present in Afghanistan ca. 2000 BC, in Harappa, Pakistan, and in northwest India in 2250–1750 BC. In the second half of the 2nd millennium BC this pulse crop appears in the Gangetic basin and southern India.^[4]

Description

The pea is a most commonly green, occasionally purple^[5] or golden yellow,^[6] pod-shaped vegetable, 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 tropical climates but do grow well in cooler high altitude tropical areas. Many cultivars reach maturity about 60 days after planting.

Worldwide pea yield

Peas have both low-growing and vining cultivars. The vining cultivars grow thin tendrils from leaves that coil around any available support and can climb to be 1–2 m high. A traditional approach to supporting climbing peas is to thrust branches pruned from trees or other woody plants upright into the soil, providing a lattice for the peas to climb. Branches used in this fashion are sometimes called pea 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 can self-pollinate.^[7]

Varieties

There are many varieties of garden pea. Some of the most common include the following:

• Alaska, 55 days (smooth seeded)
• Thomas Laxton/Laxton's Progress/Progress #9, 60-65 days
• Mr. Big, 60 days, 2000 AAS winner
• Little Marvel, 63 days, 1934 AAS winner
• Early Perfection, 65 days (This variety is the foundation of many improved varieties and crosses, including Dark-Seeded Early Perfection and Bolero, the latter being one of the most successful commercial varieties.)^[8]
• Kelvedon Wonder, 65 days, 1997 RHS AGM winner
• Homesteader/Lincoln, 67 days (heirloom, known as Greenfeast in AU, NZ)^[9]
• Wando, 68 days
• Green Arrow, 70 days
• Tall Telephone/Alderman, 75 days (heirloom, tall climber)

Other variations of P. sativum include:

• Pisum sativum var. macrocarpon is commonly known as the snow pea
• Pisum sativum var. macrocarpon ser. cv. is known as the sugar or snap pea

Both of these are eaten whole before the pod reaches maturity and are hence also known as mange-tout, French for "eat all". The snow pea pod is eaten flat, while in sugar/snap peas, the pod becomes cylindrical but is eaten while still crisp, before the seeds inside develop.

Pests and diseases

The pea leaf weevil (Latin: Sitona lineatus) is an insect that damages peas and other pod fruits. It is native to Europe, but has spread to other places such as Alberta, 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 the thorax. The weevil larvae feed on the root nodules of pea plants, which are essential to the plant's supply of nitrogen, 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.^[10]

Use

Culinary use

Frozen green peas

In early times, peas were grown mostly for their dry seeds. In modern times, however, peas are usually boiled or steamed, which breaks down the cell walls and makes the taste sweeter and the nutrients more bio-available. Along with broad beans and lentils, these formed an important part of the diet of most people in the Middle East, North Africa and Europe during the Middle Ages.^[11] 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. This was especially true in France and England, where the eating of green peas was said to be "both a fashion and a madness".^[12] New cultivars of peas were developed by the English during this time which became known as garden peas and English peas. The popularity of green peas spread to North America. Thomas Jefferson grew more than 30 cultivars of peas on his estate.^[13] With the invention of canning and freezing of foods, green peas became available year-round, and not just in the spring as before.

Peas in fried rice

Fresh peas are often eaten boiled and flavored with butter and/or spearmint as a side dish vegetable. Salt and pepper are also commonly added to peas when served. Fresh peas are also used in pot pies, salads and casseroles. Pod peas (particularly sweet cultivars called mange tout and sugar peas, or the flatter "snow peas," called hé lán dòu, 荷兰豆 in Chinese) are used in stir-fried dishes, particularly those in American Chinese cuisine.^[14] Pea pods do not keep well once picked, and if not used quickly are best preserved by drying, canning or freezing within a few hours of harvest.

In India, fresh peas are used in various dishes such as aloo matar (curried potatoes with peas) or matar paneer (paneer cheese 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. Split peas are also used to make dhal, particularly in Guyana, and Trinidad, where there is a significant population of Indians.

Dry, yellow split peas

Dried peas are often made into a soup or simply eaten on their own. In Japan, China, Taiwan and some Southeast Asian countries, including Thailand and Malaysia, peas are roasted and salted, and eaten as snacks. In the UK, dried yellow split peas are used to make pease pudding (or "pease porridge"), a traditional dish. In North America, a similarly traditional dish is split pea soup.

Pea soup is eaten in many other parts of the world, including northern Europe, parts of middle Europe, Russia, Iran, Iraq and India.^[15] In Sweden it is called ärtsoppa, and is eaten as a traditional Swedish food which predates the Viking era. This food was made from a fast-growing pea that would mature in a short growing season. Ärtsoppa was especially popular among the many poor who traditionally only had one pot and everything was cooked together for a dinner using a tripod to hold the pot over the fire.

In Chinese cuisine, pea sprouts (豆苗; dòu miáo) are commonly used in stir-fries. Pea leaves are often considered a delicacy as well.

In Greece, Turkey, Cyprus, and other parts of the Mediterranean, peas are made into a stew with meat and potatoes.

In Hungary and Serbia, pea soup is often served with dumplings and spiced with hot paprika.

In the United Kingdom, dried, rehydrated and mashed marrowfat peas, known by the public as mushy peas, are popular, originally in the north of England but now ubiquitously, and especially as an accompaniment to fish and chips or meat pies, particularly in fish and chip shops. Sodium bicarbonate is sometimes added to soften the peas. In 2005, a poll of 2,000 people revealed the pea to be Britain's 7th favorite culinary vegetable.^[16]

Processed peas are mature peas which have been dried, soaked and then heat treated (processed) to prevent spoilage—in the same manner as pasteurising. Cooked peas are sometimes sold dried and coated with wasabi, salt, or other spices.

Bioplastics

Bioplastics can be made using pea starch.

Nutritional value

Peas are high in fiber, protein, vitamins, minerals, and lutein. Dry weight is about one-quarter protein and one-quarter sugar.^[17] Pea seed peptide fractions have less ability to scavenge free radicals than glutathione, but greater ability to chelate metals and inhibit linoleic acid oxidation.^[18]

Peas in science

Pea flowers

In the mid-19th century, Austrian scientist Gregor Mendel's observations of pea pods led to the principles of Mendelian genetics, the foundation of modern genetics.^[19]

Peas in medicine

Some people are allergic to peas, as well as lentils.^[20]

Etymology

According to etymologists, the term pea was taken from the Latin pisum, which is the latinisation of the Greek πίσον (pison), neut. of πίσος (pisos), "pea".^[21][22] It was adopted into English as the noun pease (plural peasen), as in pease pudding. However, by analogy with other plurals ending in -s, speakers began construing pease as a plural and constructing the singular form by dropping the "s", giving the term "pea". This process is known as back-formation.

The name marrowfat pea for mature dried peas is recorded by the Oxford English Dictionary as early as 1733. The fact that an export cultivar popular in Japan is called Maro has led some people to assume mistakenly that the English name marrowfat is derived from Japanese.

See also

• Bean
• Black pea
• Black-eyed pea
• Dixie lee pea
• Mushy peas
• Snap pea
• Snow pea
• Split pea
• Sweet pea
• Yellow pea

Notes

References

• European Association for Grain Legume Research (AEP). Pea. http://www.grainlegumes.com/default.asp?id_biblio=52^{[dead link]}.
• Hernández Bermejo, J. E. & León, J., (1992). Neglected crops: 1492 from a different perspective, Food and Agricultural Organization of the United Nations (FAO) Contents
• Muehlbauer, F. J. and Tullu, A., (1997). Pisum sativum L. Purdue University. Pea
• Oelke, E. A., Oplinger E. S., et al. (1991). Dry Field Pea. University of Wisconsin.Dry Field Pea