The genus includes many economically important crops, garden vegetables, and herbs, including onions (A. cepa), shallots (A. cepa var. aggregatum), French shallot (A. oschaninii), leeks (A. ampeloprasum), scallions (various Allium species), Welsh onion (A. fistulosum), garlic (A. sativum), wild garlic (A. ursinum) and chives (A. schoenoprasum). Global production of onions was more than 73 million metric tons (harvested from 3.6 million hectares) in 2008, and over 22 million metric tons of garlic (from nearly 1.4 million hectares; FAOSTAT 2011).
Alliums are also planted as ornamentals. There are over 150 species and cultivars that have been developed for garden use, with colors ranging from white to blue to shades of purple, and flower heads up to the size of a softball (Davis 1993).
The Allium genus is taxonomically difficult and species boundaries are unclear. Most authorities accept about 750 species, but estimates range from 260 to 860 (Hirschegger et al. 2010, Rahn 1998). The type species for the genus is Allium sativum. The Allium genus was formerly placed in Liliaceae, and later in Alliaceae, but the 2009 classification by the Angiosperm Phylogeny Group treats Alliaceae as subfamily Allioideae of Amaryllidaceae (APG 2009).
Allium species occur in temperate climates of the northern hemisphere, except for a few species occurring in Chile (such as A. juncifolium), Brazil (A. sellovianum) or tropical Africa (A. spathaceum). They vary in height from 5 cm to 150 cm. The flowers form an umbel at the top of a leafless stalk (scape). The bulbs, which are usually tunicate (covered with a papery skin), vary in size across species, from very small (around 2–3 mm in diameter) to rather large (8–10 cm). Some species (such as Welsh onion, A. fistulosum) develop thickened leaf-bases rather than forming bulbs.
Allium species produce chemical compounds (mostly cysteine sulfoxide) that give them a characteristic onion or garlic taste and odor. Folk medicinal uses of Alliums are numerous, and considerable research has focused on identifying and examining compounds for medicinal use. Allicin, derived from garlic, is used for fighting fungal infections and parasites, lowering blood cholesterol, and promoting circulatory function (Biser 1998). Preliminary European findings suggest that a diet high in onions and garlic is correlated with reduced risk of several cancers (Galeone et al. 2006). However, some onion species are toxic to cattle, cats, dogs, sheep, and goats (Cope 2011, Merck 2011).
Some Eurasian Allium species have escaped cultivation and naturalized widely in North America. A. vineale is reported invasive in Connecticut, Maryland, North Carolina, New Jersey, Pennsylvania, Tennessee, Virginia, and West Virginia, and is classified as a noxious weed in Hawaii and California (USDA Forest Service 2006). In Arkansas, wild onions and wild garlic (Allium spp.) are classified as noxious weeds.
caterpillar of Acrolepiopsis assectella feeds within live stem of Allium
Foodplant / pathogen
colony of Botrytis dematiaceous anamorph of Botryotinia squamosa infects and damages live, white-flecked leaf (esp. towards tip) of Allium
Other: minor host/prey
Foodplant / pathogen
colony of Botrytis dematiaceous anamorph of Botrytis aclada infects and damages live leaf (base) of Allium
In Great Britain and/or Ireland:
Plant / resting place / within
puparium of Chromatomyia horticola may be found in leaf-mine (end of) of Allium
Foodplant / miner
larva of Delia platura mines leaf (lower parts) of Allium
Other: unusual host/prey
Foodplant / saprobe
Fusariella dematiaceous anamorph of Fusariella atrovirens is saprobic on Allium
Foodplant / nest
female of Hylaeus punctulatissima provisions nest with pollen of Allium
Foodplant / pathogen
Iris Yellow Spot virus infects and damages Allium
Foodplant / pathogen
Onion Yellow Dwarf virus infects and damages yellow, crinkled, flatened, twisted leaf of Allium
Plant / resting place / within
puparium of Phytomyza gymnostoma may be found in bulb of Allium
Other: sole host/prey
Foodplant / pathogen
colony of Phytophthora porri infects and damages live leaf of Allium
Remarks: season: (8-)10
Other: unusual host/prey
Foodplant / miner
larva of Scaptomyza pallida mines leaf of Allium
Remarks: season: spring, summer
Foodplant / pathogen
Sclerotium cepivorum infects and damages yellowed, wilting, died back leaf of Allium
Foodplant / saprobe
Sirexcipula coelomycetous anamorph of Sirexcipula kabatiana is saprobic on dead Allium
Evolution and Systematics
Systematics or Phylogenetics
Hirschegger et al. (2010) undertook a molecular phylogenetic analysis of the section Allium (in subgenus Allium), which includes economically important species such as garlic and leek as well as other polyploid minor crops. They focused in particular on inferring the origins of the several horticultural groups of Allium ampeloprasum.
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:1198
Specimens with Barcodes:265
Species With Barcodes:381
Members of the genus include many economically important crops and garden vegetables such as onions (A. cepa), shallots (A. cepa var. aggregatum), French shallot (A. oschaninii), leeks (A. ampeloprasum), scallions (various Allium species), and herbs such as garlic (A. sativum) and chives (A. schoenoprasum). Others are cultivated as ornamentals.
Allium is taxonomically difficult and species boundaries are unclear. Most authorities accept about 750 species. Estimates of the number of species have been as low as 260, and as high as 860. The type species for the genus is Allium sativum.
Allium species occur in temperate climates of the northern hemisphere, except for a few species occurring in Chile (such as A. juncifolium), Brazil (A. sellovianum) or tropical Africa (A. spathaceum). They can vary in height between 5 cm and 150 cm. The flowers form an umbel at the top of a leafless stalk. The bulbs vary in size between species, from very small (around 2–3 mm in diameter) to rather large (8–10 cm). Some species (such as Welsh onion, A. fistulosum) develop thickened leaf-bases rather than forming bulbs as such. Allium is a genus of perennial bulbous plants that produce chemical compounds (mostly cysteine sulfoxide) that give them a characteristic onion or garlic taste and odor. Many are used as food plants, though not all members of the genus are equally flavorful. In most cases, both bulb and leaves are edible. Their taste may be strong or weaker, depending on the species.
Allium is one of about 57 genera of flowering plants that have more than 500 species. It is by far the largest genus in the family Alliaceae in classification systems in which that family is recognized as separate from Amaryllidaceae, and is also the largest genus in Amaryllidaceae. In 2009, when the Angiosperm Phylogeny Group published the APG III system, they treated the former Alliaceae as subfamily Allioideae of Amaryllidaceae. In some of the older classification systems, Allium was placed in Liliaceae. Molecular phylogenetic studies have shown that this circumscription of Liliaceae is polyphyletic.
Allium species are herbaceous perennials with flowers produced on scapes. They grow from solitary or clustered tunicate bulbs and many have an onion odor and taste. Plants are perennialized by bulbs that reform annually from the base of the old bulb, or are produced on the ends of rhizomes or, in a few species, at the ends of stolons. A small number of species have tuberous roots. The bulbs have outer coats that are commonly brown or grey, with a smooth texture, and are fibrous, or with cellular reticulation. The inner coats of the bulbs are membranous.
Many alliums have basal leaves that commonly wither away from the tips downward before or while the plant flower, but some species have persistent foliage. Plants produce from one to twelve leaves, most species having linear, channeled or flat leaf blades. The leaf blades are straight or variously coiled, but some species have broad leaves, including A. victorialis and A. tricoccum. The leaves are sessile, and very rarely narrowed into a petiole.
The terete or flattened flowering scapes are normally persistent. The inflorescences are umbels, in which the outside flowers bloom first and flowering progresses to the inside. Some species produce bulbils within the umbels, and in some species the bulbils replace some or all the flowers. The umbels are subtended by noticeable spathe bracts, which are commonly fused and normally have around 3 veins.
The flowers are erect or in some species pendent, having six petal-like tepals produced in two whorls. The flowers have one style and six epipetalous stamens; the anthers and pollen can vary in color depending on the species. The ovaries are superior, and three-lobed with three locules.
Some bulbous alliums increase by forming little bulbs or "offsets" around the old one, as well as by seed. Several species can form many bulbils in the flowerhead; in the so-called "tree onion" or Egyptian onion (A. ×proliferum) the bulbils are few, but large enough to be pickled.
The taxonomy of Allium is poorly understood, with incorrect descriptions being widespread. Allium spicatum has been treated by many authors as Milula spicata, the only species in the monospecific genus Milula. In 2000, it was shown to be embedded in Allium.
In 2006, a phylogeny of Allium was published based on the nuclear ribosomal gene ITS. The authors of this study divided Allium into 15 subgenera and 72 sections. They defined the subgenus Rhizirideum in a much narrower sense than in previous classifications.
Subsequent molecular phylogenetic studies have shown that the 2006 classification is a considerable improvement over previous classifications, but some of its subgenera and sections are probably not monophyletic. One of these studies focused on the subgenus Amerallium which is strongly supported as monophyletic. Another study focused on Allium ampeloprasum and its relatives within the section Allium of subgenus Allium. Sampling in this study was not sufficient to test the monophyly of section Allium.
The majority of Allium species are native to the Northern hemisphere, mainly in Asia. A few species are native to Africa and Central and South America. Species grow in various conditions from dry, well-drained mineral-based soils to moist, organic soils; most grow in sunny locations but a number also grow in forests, or even in swamps / water.
Some Allium species, including A. cristophii and A. giganteum, are used as border plants for their ornamental flowers, and their "architectural" qualities. Several hybrids have been bred, or selected, with rich purple flowers. A. hollandicum 'Purple Sensation' is one of the most popular and has been given an Award of Garden Merit (H4). These ornamental onions come in a wide variety of sizes and colours, ranging from white (Allium 'Mont Blanc'), blue (A. caeruleum), to yellow (A. flavum) and purple (A. giganteum). By contrast, other species (such as invasive A. triquetrum and A. ursinum) can become troublesome garden weeds.
Various Allium species are used as food plants by the larvae of some Lepidoptera including Cabbage Moth, common swift moth (recorded on garlic), Garden Dart moth, Large Yellow Underwing moth, Nutmeg moth, Setaceous Hebrew Character moth, Turnip Moth and Schinia rosea, a moth that feeds exclusively on Allium species.
- ^ Umberto Quattrocchi. 2000. CRC World Dictionary of Plant Names volume I, page 91. CRC Press: Boca Raton; New York; Washington,DC;, USA. London, UK. ISBN 978-0-8493-2673-8 (set).
- ^ Anthony Huxley, Mark Griffiths, and Margot Levy (1992). The New Royal Horticultural Society Dictionary of Gardening. The Macmillan Press,Limited: London. The Stockton Press: New York. ISBN 978-0-333-47494-5 (set).
- ^ a b Pablo Hirschegger, Jernej Jaške, Peter Trontelj, and Borut Bohanec. 2010. "Origins of Allium ampeloprasum horticultural groups and a molecular phylogeny of the section Allium (Allium; Alliaceae)". Molecular Phylogenetics and Evolution 54(2):488-497. doi:10.1016/j.ympev.2009.08.030
- ^ a b Knud Rahn. 1998. "Alliaceae" pages 70-78. In: Klaus Kubitzki (editor). The Families and Genera of Vascular Plants volume III. Springer-Verlag: Berlin;Heidelberg, Germany. ISBN 978-3-540-64060-8
- ^ World Checklist of Selected Plant Families. (see External links below).
- ^ Allium In: Index Nominum Genericorum. In: Regnum Vegetabile (see External links below).
- ^ David G. Frodin. 2004. "History and concepts of big plant genera" Taxon 53(3):753-776.
- ^ Angiosperm Phylogeny Group (2009). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants: APG III. Botanical Journal of the Linnean Society 161(2): 105-121.
- ^ Mark W. Chase, James L. Reveal, and Michael F. Fay. "A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae and Xanthorrhoeaceae". Botanical Journal of the Linnean Society 161(2):132–136.
- ^ Eric Block, "Garlic and Other Alliums: The Lore and the Science" (Cambridge: Royal Society of Chemistry, 2010)
- ^ James L. Brewster, "Onions and Other Alliums" (Wallingford: CABI Publishing, 2008)
- ^ Dilys Davies, "Alliums: The Ornamental Onions" (Portland: Timber Press, 1992)
- ^ Haim D. Rabinowitch, Leslie Currah, "Allium Crop Sciences: Recent Advances" (Wallingford: CABI Publishing, 2002)
- ^ Penny Woodward, "Garlic and Friends: The History, Growth and Use of Edible Alliums" (South Melbourne: Hyland House, 1996)
- ^ a b http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=101086
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- ^ Nikolai Friesen, Reinhard M. Fritsch, Sven Pollner and Frank R. Blattner. 2000. "Molecular and Morphological Evidence for an Origin of the Aberrant Genus Milula within Himalayan Species of Allium (Alliacae)". Molecular Phylogenetics and Evolution 17(2):209-218. doi:10.1006/mpev.2000.0844
- ^ Nikolai Friesen, Reinhard M. Fritsch, and Frank R. Blattner. 2006. "Phylogeny and new intrageneric classification of Allium (Alliaceae) based on nuclear ribosomal DNA ITS sequences". Aliso 22(Monocots: Comparative Biology and Evolution):372-395.
- ^ Nhu H. Nguyen, Heather E. Driscoll, and Chelsea D. Specht. 2008. "A molecular phylogeny of the wild onions (Allium; Alliaceae) with a focus on the western North American center of diversity". Molecular Phylogenetics and Evolution 47(3):1157-1172. doi:10.1016/j.ympev.2007.12.006
- ^ a b Brickell, Christopher (Editor-in-chief),The Royal Horticultural Society A–Z Encyclopedia of Garden Plants, p.95, Dorling Kindersley, London, 1996, ISBN 0-7513-0303-8
- ^ RHS Plant Finder 2009–2010, p68, Dorling Kindersley, London, 2009, ISBN 978-1-4053-4176-9
- ^ Lloyd, Christopher & Rice, Graham, (1991) Garden Flowers From Seed, p45, Viking, ISBN 0-670-82455-0
- ^ http://veterinarymedicine.dvm360.com/vetmed/Medicine/Toxicology-Brief-iAlliumi-species-poisoning-in-dog/ArticleStandard/Article/detail/174478
- Pacific Bulb Society: Rhizomatous Alliums
- J. G. Dubouzet, K. Shinoda and N. Murata. Phylogeny of Allium L. subgenus Rhizirideum (G. Don ex Koch) Wendelbo according to dot blot hybridization with randomly amplified DNA probes TAG Theoretical and Applied 'Genetics. Volume 95, Number 8, December, 1997
- Haim D. Rabinowitch, Lesley Currah. Allium crop science: recent advances. CABI Publishing Series, 2002. ISBN 9780851995106
- N. Friesen, R. Fritsch and K. Bachmann. Hybrid origin of some ornamentals of Allium subgenus Melanocrommyum verified with GISH and RAPD. TAG Theoretical and Applied Genetics. Volume 95, Number 8, December, 1997
- A. Samoylov, N. Friesen, S. Pollner, P. Hanelt. Use of chloroplast DNA polymorphisms for the phylogenetic study of Allium subgenus Amerallium and subgenus Bromatorrhiza (Alliaceae) II. Feddes Repertorium Volume 110 Issue 1–2, Pages 103–109, 1999
- Block, E. (2010). Garlic and Other Alliums: The Lore and the Science. Royal Society of Chemistry. ISBN 978-0-85404-190-9.
- Brewster, J. L. (2008). Onions and Other Alliums. CABI Publishing. ISBN 978-1-84593-399-9.
- Davies, D. (1992). Alliums: The Ornamental Onions. Timber Press. ISBN 0-88192-241-2.
- Rabinowitch, H. D., Currah, L. (2002). Allium Crop Sciences: Recent Advances. CABI Publishing. ISBN 0-85199-510-1.
- Woodward, P. (1996). Garlic and Friends: The History, Growth and Use of Edible Alliums. Hyland House. ISBN 1-86447-009-7.
Nodding wild onion (Allium cernuum)
Scallions (also known as green onions, spring onions, salad onions, green shallots, onion sticks, or syboes), are the edible plants of various Allium species, all of which are "onion-like", having hollow green leaves and lacking a fully developed root bulb.
The Welsh onion (Allium fistulosum) does not form bulbs even when mature, and is grown in the West almost exclusively as a scallion or salad onion, although in Asia this species is of primary importance and used both fresh and in cooking. "Scallion" is also used for young plants of the common onion (A. cepa var. cepa) and shallot (A. cepa var. aggregatum, formerly A. ascalonicum), harvested before bulbs form, or sometimes when slight bulbing has occurred. Most of the cultivars grown in the West primarily as salad onions or scallions belong to A. cepa var. cepa. Other species sometimes used as scallions include A. ×proliferum and A. ×wakegi.
The words scallion and shallot are related and can be traced back to the Greek askolonion as described by the Greek writer Theophrastus. This name, in turn, seems to originate from the Philistine town of Ascalon (modern-day Ashkelon in Israel). The shallots themselves apparently came from farther east of Europe.
Harvested for their taste, they are milder than most onions. They may be cooked or used raw as a part of salads or Asian recipes. Diced scallions are used in soup, noodle and seafood dishes, as well as sandwiches, curries or as part of a stir fry. To make many Eastern sauces, the bottom quarter-inch of scallions are commonly removed before use. Cut at root level.
In Vietnam, Welsh onion is important to cook dưa hành (a kind of kimchi) served for Tết festival. A kind of sauce, mỡ hành (Welsh onion fried in oil), is used in some dishes such as cơm tấm, bánh ít, cà tím nướng and others. Welsh onion is the only ingredient in the dish cháo hành (a dish to treat the common cold).
White Lisbon Winter Hardy - an extra-hardy variety for overwintering.
- ^ Fritsch, R.M.; N. Friesen (2002). "Chapter 1: Evoluion, Domestication, and Taxonomy". In H.D. Rabinowitch and L. Currah. Allium Crop Science: Recent Advances. Wallingford, UK: CABI Publishing. p. 18. ISBN 0-85199-510-1.
- ^ Fritsch, R.M.; N. Friesen (2002). "Chapter 1: Evoluion, Domestication, and Taxonomy". In H.D. Rabinowitch and L. Currah. Allium Crop Science: Recent Advances. Wallingford, UK: CABI Publishing. p. 20. ISBN 0-85199-510-1.
- ^ Brewster, James L. (1994). Onions and other vegetable alliums (1st ed.). Wallingford, UK: CAB International. p. 15. ISBN 0-85198-753-2.
- ^ Allium Crop Science: recent advances at Google Books, last retrieved 2007-03-31
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