Taxonomy of the Leek [Allium porrum (L.) J. Gay] according to Cronquist System
Superdominium/Superdomain: Biota
Dominium/Dominio: Eukaryota Whittaker & Margulis,1978
Regnum/Kingdom: Plantae Haeckel, 1866
Subregnum/SubKingdom: Viridaeplantae Cavalier-Smith, 1998
Superdivisio/Superdivision: Spermatophyta Gustav Hegi, 1906
Divisio/Division or Phylum: Tracheophyta Sinnott, 1935 ex Cavalier-Smith, 1998 -
Subdivisio/Subdivision: Magnoliophytina Frohne & U. Jensen ex Reveal, 1996
Classis/Class: Liliopsida Brongn., 1843
Subclassis/Subclass: Liliidae J.H. Schaffn.,1911
SuperOrdo/SuperOrder: Lilianae Takht., 1967
Ordo/Order: Amaryllidales Bromhead, 1840
Familia/Family: Alliaceae J. Agardh, 1858
Subfamilia/Subfamily: Allioideae Herb., 1837
Tribus/Tribe: Allieae Dumort., 1827
Subtribus/Subtribe: Alliinae Parl, 1852
Genus/Genere: Allium L. 1753
Species: Allium porrum (L.) J. Gay

The synonyms of this species are:
The common names in the world are the following: Generality
Allium porrum, is a vegetable which belongs, along with the onion and garlic, to the Alliaceae family.
The edible part of the leek plant is a bundle of leaf sheaths which is sometimes called a stem or stalk. Rather than forming a tight bulb (it is a short stem with fleshy leaves or leaf bases) like the onion, the leek produces a long cylinder of bundled leaf sheaths which are generally blanched by pushing soil around them (trenching). They are often sold as small seedlings in flats which are started off early in greenhouses, to be planted out as weather permits. Once established in the garden, leeks are hardy; many varieties can be left in the ground during the winter to be harvested as needed.
Dried specimens from archaeological sites in ancient Egypt, as well as wall carvings and drawings, led Zohary and Hopf to conclude that the leek was a part of the Egyptian diet “from at least the 2nd millennium BCE onwards.” They also allude to surviving texts that show it had been also grown in Mesopotamia from the beginning of the 2nd millennium BCE. The leek was the favourite vegetable of the Emperor Nero, who consumed it in soup or in oil, believing it beneficial to the quality of is oil.

The leek is a vegetable crops cultivated in all Italy and native of the Mediterranean, probably from Near Orient. The stem, constituted from the foliar sheaths placed one on top of the other, is used. Leek is employed raw, like seasoned, or cooked.
The leek is a biennial plant cultivated like annual. High 40-80 cm, the plant has a fasciculate radical apparatus with several thin roots that are originated from a small stem.
In the stem the linear and lanceolate leaves are inserted, closely overlapped ones to the others in the base portion of them, and placated in two opposite series. The leaves are green-dark or green-yellowish and they grouped to form a kind of pseudo-stem (figure 1).

Figure 1 – Plant of leek.

In the successive year to that in which the showing is carried out, the floral scape is formed, high up to 80 cm, carrying to the above extremity a globosely and umbrella inflorescence formed of a number many elevated of flowers white, or greenish, or rose or lilac formed from three pieces and forming the in inflorescence (figure 2).

Figure 2 – Inflorescence of leek in pollination stage.

The seeds are small, black and angular (figure 3).

Figure 3 – Seeds of leek.

Climate: it appreciate moderated climates, but it well supports also the cold.
Soil: the leek well grows in light and rather fertile soils.
Varieties: in relation to the origin of leek the Italian varieties are the best. Some italian varieties are cited of following:
  • “Lungo gigante d’inverno”,
  • “Elefante”,
  • “Mostruoso di Carentan”,
  • “Genovese”,
  • “Grosso Corto Mostruoso di Rouen”,
  • “Grosso Corto d'Estate”,
  • “Gigante d'Italia”.
Cultivation succession: it does not have to follow cabbages and potatoes. It does not have to be cultivated newly on the same soil before that they are passed at least four years from the before cultivation.
Intercropping: con cavoli, lattughe, finocchi, carote (figure 4).

Figure 4 – Leek cultivation with other crops.

Showing and put to dwelling: the showing happens in seedbed to a depth of few millimetres. Showing is carried out to warm bed in December-January or in open field from March to June, directly in the garden from March to July.
When it plantlets have formed the quarter-fifth leaf and the diameter of the false stem becomes approximately 1 cm, the transplant is carried out. This operation is made after to have slightly trimmed the leaves, in cloudy days or after the sunset.
The soil is prepared by means of a deep digging and with follow-up hoeing. during of which 30-40 g/m2 of complex fertilizer (6-12-9) are give.
After the transplant some weedings and an earthing up are carried out, watering the soil if it is dry.
The distance between transplanting plantlets on the row is 15-20 cm, and 25-30 cm between the rows.
Fertilization: matured manure (4 kg/m2) it must be buried in summer-autumn to the depth of 30 cm. In the course of the cultivation is carried out also a cover fertilization, with a limited quantitative of calcium nitrate; it is advisable not to exceed in the nitrogen fertilizer because, in this case, they would be obtained leeks little preservable during the storage.
Cultivation cures: the soil must be held always free from infesting plants, carrying out repeated weedings and hoeing.
Irrigations: In the periods in which it does not rain it is necessary to water abundantly but to avoid the water stagnations.
Harvest and storage: the harvest is carried out in various ages, according to the showing transplant period; the periods of harvest occur in summer, autumn and winter. The leek can be preserved in optimal conditions, for enough long periods of time. Before to use the leek, the external leaves must be eliminated.

The edible portions of the leek are the white onion base and light green stalk. The dark green portion is usually discarded since it has less flavour. As the leek grows, this part becomes woody and very chewy. One of the most popular uses for the whites and light green stalks is for adding flavour to stock. Chefs rarely use the darker part of the leek for stock because of its bitterness. However, a few leaves are sometimes tied with twine and other herbs to form a bouquet garni. The bouquet garni is a bundle of herbs usually tied together with string and mainly used to prepare soup, stock, and various stews. The bouquet is boiled with the other ingredients, but is removed prior to consumption. There is no generic recipe for bouquet garni, but most recipes include parsley, thyme and bay leaf. Depending on the recipe, the bouquet garni may include basil, burnet, chervil, rosemary, peppercorns, savory and tarragon. Sometimes vegetables such as carrot, celery (leaves or stem), celeriac, leek, onion and parsley root are also included in the bouquet.
Leek has a mild onion-like taste, less bitter than scallion. The taste might be described as a mixture of mild onion and cucumber, with a fresh smell similar to scallion. In its raw state, the vegetable is crunchy and firm.
Leek is typically chopped into slices 5–10 mm thick. The slices have a tendency to fall apart, due to the layered structure of the leek. There are different ways of preparing the vegetable:
  • Boiled, which turns it soft and mild in taste.
  • Fried, which leaves it more crunchy and preserves the taste.
  • Raw, which can be used in salads, doing especially well when they are the prime ingredient.
Leeks are an ingredient of cock-a-leek soup, leek and potato soup and vichyssoise, along with leek soup.
Because of their symbolism in Wales (see below), they have come to be used extensively in that country’s cuisine. Elsewhere in Britain, leeks have come back into favour only in the last fifty years or so, having been overlooked for several centuries.

Historical consumption
Dried specimens from archaeological sites in ancient Egypt, as well as wall carvings and drawings, led Zohary and Hopf to conclude that the leek was a part of the Egyptian diet “from at least the 2nd millennium BCE onwards.” They also allude to surviving texts that show it had been also grown in Mesopotamia from the beginning of the 2nd millennium BCE. The leek was the favorite vegetable of the Emperor Nero, who consumed it in soup or in oil, believing it beneficial to the quality of his voice.
Cultural significance
The leek is one of the national emblems of Wales, worn along with the daffodil (in Welsh, the daffodil is known as "Peter's Leek", Cenhinen Bedr) on St. David’s Day. According to one legend, King Cadwaladr of Gwynedd ordered his soldiers to identify themselves by wearing the vegetable on their helmets in an ancient battle against the Saxons that took place in a leek field. This story may have been made up by the English poet Michael Drayton, but it is known that the leek has been a symbol of Wales for a long time; Shakespeare, for example, refers to the custom of wearing a leek as an “ancient tradition” in Henry V. In the play, Henry tells Fluellen that he is wearing a leek “for I am Welsh, you know, good countryman.” The 1985 and 1990 British on
e pound coins bear the design of a leek in a coronet, representing Wales. Perhaps the most visible use of the leek, however, is as the cap badge of the Welsh Guards, a regiment within the Household Division of the British Army.
In Romania, the leek is also widely considered a symbol of Oltenia, a historical region in the south-western part of the country.

Diseases and Pests
  • Downy mildew (caused by Peronospora destructor) and purple blotch (caused by Alternaria porri) are the major leaf diseases affecting leeks. Very few chemicals are registered for controlling these diseases; local resellers should be able to provide information on which products are registered for use on leeks.
  • White rot (Sclerotium cepivorum), pink root (Pyrenochaeta terrestis) and fusarium (Fusarium spp.) are the major soil-borne diseases affecting leeks. There are no products currently registered in Italy for the control of these diseases on leeks.
    If diseases are an ongoing problem, lower plant densities (thinner plantings) and adequate crop nutrition may help to reduce their incidence.
  • Leek Rust. The signs are powdery rust coloured deposit on leaves from fungal infection, leaves later turn yellow.
    Caused through lack of potassium in the soil. Plants may be saved with copper based spray like a bordeaux mixture, if not feed infected plants to animals do not compost.
  • Onion Maggot Fly. The signs are holes and maggots in the leeks, the maggot will completely consume the inside of a leek before moving on to the next leek, killing them in succession. A second attack later in August will attack the maturing plants causing them to become limp and turn yellow and allowing a bacterial infection into the plants so rendering them useless.
    The prevention and cure consist in a good housekeeping by vigilante crop rotation, but if attacked the plants will be rendered useless so remove all and burn. Disturb affected soil and allow preditors in to mop up existing eggs and maggots.
  • Onion Thrips. The signs are foliage being eaten from inside by thrip larvae causing it to be discoloured and deformed, attacks coincide with warm weather. The prevention and cure consist in a good housekeeping by vigilante crop rotation, but if attacked the plants will be rendered useless so remove all and burn.
  • Nematodes treatments and other detergent sprays are available, but nothing beats crop rotation and regular inspections.
  • Leek Moths. The signs are holes through leaves. Disfiguring white streaks on leaves as the leaves are full of now hollowed out tunnels from the moth maggot.
    The prevention and cure consist in to remove any infected plants which may be all of them and feed to animals do not compost.
An experiment was conducted in the farm of the Vegetable Crop Center, in 1992, to evaluate the incidence of onion thrips (Thrips tabaci), purple leek spottedness (Alternaria porri) and leek rust (Puccinia porri) as affected by various agronomic practices, such as direct sowing, growing with seedlings, and covering of plants with PP film (polypropylene) cover. Leek plants were also sprayed with Dursban E-48 (chlorpyrifos), Basudin 40 WP (diazinon) and Dithane M-45 (mancozeb). During experiment, the yellow sticky traps were replaced twice a week, and the quantity of insect pests on the traps was recorded. The diseases were also checked twice a week. The number of onion thrips was highest in the field where no insecticide was used (15% of the plants were damaged by thrips). Lesser extent of damage caused by feeding of onion thrips was found in plots with PP cover (11%) and those sprayed with insecticides (10%). In general, infestation by onion thrips was greater in the experimental field of the Vegetable Crop Center, while the occurrence of purple leek spottedness was greater in Battipaglia area.


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