Spinach (Spinacia oleracea) is a leafy green flowering plant native to central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common edible vegetable consumed either fresh, or after storage using preservation techniques by canning, freezing, or dehydration. It may be eaten cooked or raw, and the taste differs considerably; the high oxalate content may be reduced by steaming.

It is an annual plant (rarely biennial), growing as tall as 30 cm (1 ft). Spinach may overwinter in temperate regions. The leaves are alternate, simple, ovate to triangular, and very variable in size: 2–30 cm (1–12 in) long and 1–15 cm (0.4–5.9 in) broad, with larger leaves at the base of the plant and small leaves higher on the flowering stem. The flowers are inconspicuous, yellow-green, 3–4 mm (0.1–0.2 in) in diameter, and mature into a small, hard, dry, lumpy fruit cluster 5–10 mm (0.2–0.4 in) across containing several seeds.

In 2021, world production of spinach was 32 million tonnes, with China alone accounting for 92% of the total.[1]

Originally from Persian the word aspānāḵ entered European languages from Latin, which borrowed it from Arabic.[2] The English word "spinach" dates to the late 14th century from OF espinache.[3]

Common spinach (S. oleracea) was long considered to be in the family Chenopodiaceae, but in 2003 that family was merged into the Amaranthaceae in the order Caryophyllales.[4][5] Within the family Amaranthaceae sensu lato, Spinach belongs to the subfamily Chenopodioideae.[6]

As opposed to the great majority of the flowering plants or plants used as vegetables, spinach is a dioicous plant, meaning different plants can have either female or male flowers.[a][7]

Pollination occurs via wind anemophily, because the flowers are small and green and thus they are unattractive to pollinators. Therefore, the pollen evolved to be very small and light so it can be transported to large distances, often miles away.

Spinach male flowers

Spinach female flowers

Round seeds of the 'Monnopa' cultivar

Spiky seeds of the 'Erste Ernte' cultivar

Spinach is thought to have originated about 2,000 years ago in ancient Persia from which it was introduced to India and later to ancient China via Nepal in 647 AD as the "Persian vegetable".[8] In AD 827, the Saracens introduced spinach to Sicily.[9] The first written evidence of spinach in the Mediterranean was recorded in three 10th-century works: a medical work by al-Rāzī (known as Rhazes in the West) and in two agricultural treatises, one by Ibn Waḥshīyah and the other by Qusṭus al-Rūmī. Spinach became a popular vegetable in the Arab Mediterranean and arrived in Spain by the latter part of the 12th century, where Ibn al-ʻAwwām called it raʼīs al-buqūl, 'the chieftain of leafy greens'.[10] Spinach was also the subject of a special treatise in the 11th century by Ibn Ḥajjāj.[11][better source needed]

Spinach first appeared in England and France in the 14th century, probably via Spain, and gained common use because it appeared in early spring when fresh local vegetables were not available.[8] Spinach is mentioned in the first known English cookbook, the Forme of Cury (1390), where it is referred to as 'spinnedge' and 'spynoches'.[8][12] During World War I, wine fortified with spinach juice was given to injured French soldiers with the intent to curtail their bleeding.[8][13]

Spinach is eaten both raw, in salads, and cooked in soups, curries, or casseroles.

Raw spinach is 91% water, 4% carbohydrates, 3% protein, and contains negligible fat. In a 100 g (3.5 oz) serving providing only 23 calories, spinach has a high nutritional value, especially when fresh, frozen, steamed, or quickly boiled. It is a rich source (20% or more of the Daily Value, DV) of vitamin A, vitamin C, vitamin K, magnesium, manganese, iron and folate. Spinach is a moderate source (10–19% of DV) of the B vitamins, riboflavin and vitamin B6, vitamin E, calcium, potassium, and dietary fiber (table).

100 g of spinach contains over four times the recommended daily intake of vitamin K. For this reason, individuals taking the anticoagulant warfarin, which acts by inhibiting vitamin K, are instructed to minimize consumption of spinach (and other dark green leafy vegetables) to avoid blunting the effect of warfarin.[14]

Although spinach contains moderate amounts of iron and calcium, it also contains oxalates, which may inhibit absorption of calcium and iron in the stomach and small intestine. Cooked spinach has lower levels of oxalates, and its nutrients may be absorbed more completely.[15][16]

Cooking spinach significantly decreases its vitamin C concentration, as vitamin C is degraded by heating. Folate levels may also be decreased, as folate tends to leach into cooking liquid.[17]

Spinach is rich in nitrates and nitrites, which may exceed safe levels if spinach is over-consumed.[18]

In 2021, world production of spinach was 32 million tonnes, with China alone accounting for 92% of the total.[1]

Fresh spinach is sold loose, bunched, or packaged fresh in bags. Fresh spinach loses much of its nutritional value with storage of more than a few days.[19] Fresh spinach is packaged in air, or in nitrogen gas to extend shelf life. While refrigeration slows this effect to about eight days, fresh spinach loses most of its folate and carotenoid content over this period of time. For longer storage, it is canned, or blanched or cooked and frozen.[19]

Some packaged spinach is exposed to radiation to kill any harmful bacteria. The Food and Drug Administration approves of irradiation of spinach leaves up to 4.0 kilograys, having no or only a minor effect on nutrient content.[20]

Spinach may be high in cadmium contamination depending on the soil and location where the spinach is grown.[21]

The comics and cartoon character Popeye the Sailor Man is portrayed as gaining strength by consuming canned spinach.[22] The accompanying song lyric is: "I'm strong to the finich [sic], 'cuz I eats me spinach."[23] This is usually attributed to the iron content of spinach, but in a 1932 strip, Popeye states that "spinach is full of vitamin A" and that is what makes people strong and healthy.[24]