کَرَفْس گیاهی است با نام علمی Apium graveolens. این گیاه در آشپزی کاربرد داردو ارتفاع آن تا یک متر میرسد.
کرفس دارای مواد معدنی منیزیوم و پتاسیم میباشد که برای آرامش اعصاب و بیماریهای روحی نظیر (Vertigo) مفید میباشند. کرفس همچنین دارای مقدار زیادی ویتامینهای ک. و سی است که آنتی اکسیدان بوده، موجب کاهش تورم یاختههای بدن، سمزدایی و مبارزه با روماتیسم و بیماریهای سرطانی میگردند.
کرفس از معدود گیاهانی است که میتوان آن را همزمان با میوهها و گیاهان دیگر مصرف کرد و باعث دشواری در گوارش نمیگردد. برای نمونه با آب انگور و سیب (برای مبارزه با روماتیسم)، با زنجبیل (برای مبارزه با میگرن و سردرد) و با لیموترش (برای مبارزه با سرماخوردگی و قند بالای خون).
کرفس مقدار کمی کالری ولی مقدار زیادی الیاف غذایی دارد که اگرچه گواردن کامل آنرا سخت میکند، اما آن را از معدود غذاهایی میکند که کالری منفی دارند و باعث کمبود اشتها و کاهش وزن میشوند.
کرفس و یا تخم کرفس هم ماهیچهها را منبسط میکنند (مانند ماهیچههای جداره رگها) و هم ادرارآور میباشند و به این واسطه کارشناسان تغذیه بر این عقیدهاند که کرفس بهترین ماده غذایی برای مبارزه با مشکلات کلیه و مثانه، همچون عفونت مجاری ادرار، نقرس (اسید اوریک بالا)، سنگ کلیه و همچنین فشار خون بالا میباشد. کرفس در کاهش چربی خون بسیار سودمند است.
کرفس منبعی بسیار غنی از ویتامین C است. ویتامین C عملکرد سیستم ایمنی بدن را بهبود داده سبب افزایش مقاومت بدن در برابر بیماری ها می گردد و یکی از بارزترین نمونه های آن پیشگیری از ابتلا به سرماخوردگی و کاهش علائم و شدت بیماری در صورت ابتلا است. لذا توصیه می شود به خصوص افرادی که بیشتر مستعد سرماخوردگی هستند در فصل پاییز و زمستان از این سبزی استفاده کنند. 
کاهش فشار خون[ویرایش]
مصرف آب کرفس به میزان یک لیوان در روز به مدت یک هفته به طور معنیداری در کاهش فشارخون تأثیرگذار است. ترکیبی به نام phthalide در کرفس وجود دارد که با تأثیر بر عضلات اطراف شریانها منجر به انبساط و گشادی عروق و در نتیجه کاهش فشارخون میشود. این ترکیب همچنین منجر به کاهش هورمونهای محرک و منقبض کننده عروق میشود. جالب اینجاست که با تمام این تأثیرات، مصرف کرفس باعث کاهش فشارخون به کمتر از میزان نرمال نمیگردد. 
پیشگیری از سرطان[ویرایش]
کرفس دارای حداقل 8 ماده ضد سرطان شناخته شده است. که از مهم ترین آن ها می توان به استینلیک اسید اشاره کرد که نشان داده شده رشد سلولهای سرطانی را مهار میکند. فنولیک اسید که فعالیت پروستاگلاندینها را مهار میکند و از طریق مهار تأثیر پروستاگلاندینها بر رشد سلولهای تومور یک ضد سرطان به حساب میآید و نیز کومارین که با ممانعت از عمل رادیکالهای آزاد از تخریب سلولها جلوگیری میکند، از دیگر ضد سرطانهای موجود در آب کرفساند.
This article is about the vegetable. For the software, see Celery Task Queue.
Celery (Apium graveolens) is a cultivated plant, variety in the family Apiaceae, commonly used as a vegetable. Depending on location, either its stalks, or its hypocotyl, are eaten and used in cooking.
In North America the dominant variety most commonly available in trade is "celery", Apium graveolens var. dulce, whose stalks are eaten raw, or as an ingredient in salads, or as a flavoring in soups, stews, and pot roasts.
In Europe the dominant variety most commonly available in trade is celeriac (Apium graveolens var. rapaceum) whose hypocotyl forms a large bulb which is eaten cooked, or as a the major ingredient in a soup. It is commonly, but incorrectly, called "celery root". The leaves of rapaceum are used as seasoning, but the stalks find only marginal use.
Celery seed is also used as a spice. The plant grows to 1 m (3.3 ft) tall.
Celery leaves are pinnate to bipinnate with rhombic leaflets 3–6 cm (1.2–2.4 in) long and 2–4 cm broad. The flowers are creamy-white, 2–3 mm in diameter, and are produced in dense compound umbels. The seeds are broad ovoid to globose, 1.5–2 mm long and wide. Modern cultivars have been selected for solid petioles, leaf stalks. A celery stalk readily separates into "strings" which are bundles of angular collenchyma cells exterior to the vascular bundles.
First attested in English in 1664, the word "celery" derives from the French céleri, in turn from Italian seleri, the plural of selero, which comes from Late Latin selinon, the latinisation of the Greek σέλινον (selinon), "parsley". The earliest attested form of the word is the Mycenaean Greek se-ri-no, written in Linear B syllabic script.
The plants are raised from seed, sown either in a hot bed or in the open garden according to the season of the year, and, after one or two thinnings and transplantings, they are, on attaining a height of 15–20 cm (5.9–7.9 in), planted out in deep trenches for convenience of blanching, which is effected by earthing up to exclude light from the stems.
In the past, celery was grown as a vegetable for winter and early spring; it was perceived as a cleansing tonic, welcomed to counter the salt-sickness[further explanation needed] of a winter diet. By the 19th century, the season for celery had been extended, to last from the beginning of September to late in April.
In North America, commercial production of celery is dominated by the cultivar called 'Pascal' celery. Gardeners can grow a range of cultivars, many of which differ from the wild species, mainly in having stouter leaf stems. They are ranged under two classes, white and red. The stalks grow in tight, straight, parallel bunches, and are typically marketed fresh that way, without roots and just a little green leaf remaining.
In Europe the dominant variety of celery most commonly grown is Apium graveolens var. rapaceum grown because its hypocotyl forms a large bulb, correctly called celeriac, but often incorrectly called celery root. The leaves are used as seasoning, and the stalks find only marginal use.
The wild form of celery is known as "smallage". It has a furrowed stalk with wedge-shaped leaves, the whole plant having a coarse, earthy taste, and a distinctive smell. The stalks are not usually eaten (except in soups or stews in French cuisine), but the leaves may be used in salads, and its seeds are those sold as a spice. With cultivation and blanching, the stalks lose their acidic qualities and assume the mild, sweetish, aromatic taste particular to celery as a salad plant.
Harvesting and storage
Harvesting occurs when the average size of celery in a field is marketable; due to extremely uniform crop growth, fields are harvested only once. The petioles and leaves are removed and harvested; celery is packed by size and quality (determined by colour, shape, straightness and thickness of petiole, stalk and midrib[clarification needed] length and absence of disease, cracks, splits, insect damage and rot). Under optimal conditions, celery can be stored for up to seven weeks between 0 to 2 °C (32 to 36 °F). Inner stalks may continue growing if kept at temperatures above 0 °C (32 °F). Freshly cut petioles of celery are prone to decay, which can be prevented or reduced through the use of sharp blades during processing, gentle handling, and proper sanitation.
In the past, restaurants used to store celery in a container of water with powdered vegetable preservative, but it was found that the sulfites in the preservative caused allergic reactions in some people. In 1986, the U.S. Food and Drug Administration banned the use of sulfites on fruits and vegetables intended to be eaten raw.
Celery is used around the world as a vegetable. In North America for the crisp petiole (leaf stalk). In Europe the hypocotyl is used as a root vegetable. The leaves are strongly flavoured and are used less often, either as a flavouring in soups and stews or as a dried herb.
In temperate countries, celery is also grown for its seeds. Actually very small fruit, these "seeds" yield a valuable volatile oil used in the perfume and pharmaceutical industries. They also contain an organic compound called apiol. Celery seeds can be used as flavouring or spice, either as whole seeds or ground.
The seeds can be ground and mixed with salt, to produce celery salt. Celery salt can also be made from an extract of the roots, or using dried leaves. Celery salt is used as a seasoning, in cocktails (notably to enhance the flavour of Bloody Mary cocktails), on the Chicago-style hot dog, and in Old Bay Seasoning.
Celery, onions, and bell peppers are the "holy trinity" of Louisiana Creole and Cajun cuisine. Celery, onions, and carrots make up the French mirepoix, often used as a base for sauces and soups. Celery is a staple in many soups, such as chicken noodle soup.
The use of celery seed in pills for relieving pain was described by Aulus Cornelius Celsus around AD 30. Celery seeds contain a compound, 3-n-butylphthalide, that has been demonstrated to lower blood pressure in rats.
Bergapten in the seeds can increase photosensitivity, so the use of essential oil externally in bright sunshine should be avoided. The oil and large doses of seeds should be avoided during pregnancy, as they can act as a uterine stimulant. Seeds intended for cultivation are not suitable for eating as they are often treated with fungicides.
Celery is used in weight-loss diets, where it provides low-calorie dietary fibre bulk. Celery is often incorrectly thought to be a "negative-calorie food," the digestion of which burns more calories than the body can obtain. In fact, eating celery provides positive net calories, with digestion only consuming a small proportion of the calories taken in.
Celery is among a small group of foods (headed by peanuts) that appear to provoke the most severe allergic reactions; for people with celery allergy, exposure can cause potentially fatal anaphylactic shock. The allergen does not appear to be destroyed at cooking temperatures. Celery root—commonly eaten as celeriac, or put into drinks—is known to contain more allergen than the stalk. Seeds contain the highest levels of allergen content. Exercise-induced anaphylaxis may be exacerbated. An allergic reaction also may be triggered by eating foods that have been processed with machines that have previously processed celery, making avoiding such foods difficult. In contrast with peanut allergy being most prevalent in the US, celery allergy is most prevalent in Central Europe. In the European Union, foods that contain or may contain celery, even in trace amounts, must be clearly marked as such.
Daniel Zohary and Maria Hopf note that celery leaves and inflorescences were part of the garlands found in the tomb of pharaoh Tutankhamun (died 1323 BC), and celery mericarps dated to the seventh century BC were recovered in the Heraion of Samos. However, they note "since A. graveolens grows wild in these areas, it is hard to decide whether these remains represent wild or cultivated forms." Only by classical times is it certain that celery was cultivated.
M. Fragiska mentions an archeological find of celery dating to the 9th century BC, at Kastanas; however, the literary evidence for ancient Greece is far more abundant. In Homer's Iliad, the horses of the Myrmidons graze on wild celery that grows in the marshes of Troy, and in Odyssey, there is mention of the meadows of violet and wild celery surrounding the cave of Calypso.
A chthonian symbol among the ancient Greeks, celery was said to have sprouted from the blood of Kadmilos, father of the Cabeiri, chthonian divinities celebrated in Samothrace, Lemnos, and Thebes. The spicy odour and dark leaf colour encouraged this association with the cult of death. In classical Greece, celery leaves were used as garlands for the dead, and the wreaths of the winners at the Isthmian Games were first made of celery before being replaced by crowns made of pine. According to Pliny the Elder in Achaea, the garland worn by the winners of the sacred Nemean Games was also made of celery. The Ancient Greek colony of Selinous (Greek: Σελινοῦς, Selinous), on Sicily, was named after wild parsley that grew abundantly there; Selinountian coins depicted a parsley leaf as the symbol of the city.
The name "celery" retraces the plant's route of successive adoption in European cooking, as the English "celery" (1664) is derived from the French céleri coming from the Lombard term, seleri, from the Latin selinon, borrowed from Greek.
Celery's late arrival in the English kitchen is an end-product of the long tradition of seed selection needed to reduce the sap's bitterness and increase its sugars. By 1699, John Evelyn could recommend it in his Acetaria. A Discourse of Sallets: "Sellery, apium Italicum, (and of the Petroseline Family) was formerly a stranger with us (nor very long since in Italy) is an hot and more generous sort of Macedonian Persley or Smallage...and for its high and grateful Taste is ever plac'd in the middle of the Grand Sallet, at our Great Men's tables, and Praetors feasts, as the Grace of the whole Board".
Celery has made a surprising appearance in football folklore. Supporters of English Premier League team Chelsea and Football League team Gillingham regularly sing songs about the vegetable and are famed for throwing celery during matches. This has also given rise to the "Chelsea Cocktail", a pint of Guinness garnished with a stick of celery.
In the television program Doctor Who, the Fifth incarnation of The Doctor (played by Peter Davison), was noted for wearing a stalk of celery on his lapel, claiming it at one point to be an excellent restorative.