Leek (Allium ampeloprasum Leek Group, Syn. Allium porrum), also Leeks, Broad leek, Winter leeks, Borree, Welsh onion, Mean leek, Spanish leek, Aschlauch, Meat leek is a group of varieties of the Mediterranean allium (Allium ampeloprasum).  This vegetable belongs to the genus Allium in the onion family (Alliaceae).
In the past, the term "leek" was mainly used in German-speaking countries. In recent years, however, the name "leek", which used to be common only in the south, has become more and more widespread. 
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It is a biennial herbaceous plant that reaches growth heights of 60 to 80 centimeters. Leeks do not have an onion, but the natural form has a bulb. The linear to lanceolate leaves are 1 to 5 cm wide.
The inflorescence has a smooth shaft and a many-petaled, long-billed sheath, which is longer than the large, umbellate, globose, many-flowered inflorescence. The hermaphrodite flowers are radially symmetrical. The white to light purple petals are 4.5 to 5 mm long and 2 to 2.3 mm wide. It is formed ovoid capsule fruits. Sometimes in the inflorescence are formed brood tubers. 
Leeks contain vitamin C, vitamin K and folic acid, as well as the trace elements potassium, calcium, magnesium, iron and manganese. The antioxidant and antibacterial sulfur compound allicin, which is formed from alliin and the catalyzing enzyme allinase, causes the intense smell and taste of leeks.
Leeks are used both as a vegetable (mostly winter leeks) and as a culinary spice (mostly summer leeks); you can eat them as a vegetable or salad, or use them with carrots and celery as a seasoning in soups (in greens). 
The leek is a cultivated form of the field leek (Allium ampeloprasum), which occurs wild in the Mediterranean region and is cultivated in various forms.
Leeks are already around 2100 v. Chr. known; the Sumerian ruler Urnammu had it cultivated in the gardens of the city of Ur.
Leeks were also known in ancient Egypt; they are said to have served as food for the workers who built the pyramids.
In ancient times, the leek was appreciated throughout the Mediterranean area. The Roman emperor Nero is said to have appreciated leeks for the mustard oil they contain; because of this passion, Nero was also known as "Porrophagus" (Leek eater) denotes.
Leek was so sacred in ancient Germanic ritual that it gave the name to a rune.
It is probable that the leek came to Central Europe from Italy in the Middle Ages. In the British Isles, leeks are said to have been used by the British king Cadwallader around 640 as a distinguishing mark for his troops.
Leeks are still grown mainly in the Mediterranean region and in Europe, although in Germany they are mainly grown in North Rhine-Westphalia. It is sown in spring, transplanted around St. John’s Day (24. June) 24 cm from each other, and in the winter, in the garden, bake it quite deep so that the leaves bleach, or leave it in the country and cover it with straw.
Plants tolerate different neighbors growing directly adjacent to them differently:
- Good neighbors are: Endive, strawberry, chamomile, cabbage, kohlrabi, lettuce, carrot, salsify, celery, tomato.
- Bad neighbors are: Bean, peas, beet.
A volume of stories by Arno Schmidt from 1959 has the title "Roses and Leeks".