The generic name Allium is the Latin word for garlic, and Linnaeus first described the genus Allium in 1753. Some sources refer to Greek αλεω (aleo, to avoid) by reason of the smell of garlic. The cooking and consumption of parts of the plants is due to the large variety of flavours and textures of the species. Various Allium have been cultivated from the earliest times and about a dozen species are economically important as crops, or garden vegetables, and an increasing number of species are important as ornamental plants. The inclusion of a species to the genus Allium is taxonomically difficult and species boundaries are unclear. Estimates of the number of species have been as low as 260, and as high as 979. Most authorities accept about 750 species. 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), and tropical Africa (A. spathaceum). They 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 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.
Plants of the Allium genus produce chemical compounds (mostly derived from cysteine sulfoxides) that give them a characteristic (alliaceous) onion or garlic taste and odor. Many are used as food plants, though not all members of the genus are equally flavorous. In most cases, both bulb and leaves are edible and the taste may be strong or weak, depending on the species and on ground sulfur (usually as sulfate) content. In the rare occurrence of sulfur-free growth conditions, all Allium species lose their usual pungency altogether.
In the APG III classification system, Allium is placed in the family Amaryllidaceae, subfamily Allioideae (formerly the family Alliaceae). In some of the older classification systems, Allium was placed in Liliaceae. Molecular phylogenetic studies have shown this circumscription of Liliaceae is not monophyletic.
Allium is one of about fifty-seven genera of flowering plants with more than 500 species. It is by far the largest genus in the Amaryllidaceae, and also in the Alliaceae in classification systems in which that family is recognized as separate.
- Description 1
- History 2.1
- Subdivision 2.2
- Subgenera 2.3
- Species 2.4
- Distribution and habitat 3
- Ecology 4
- Ornamental 5.1
- Toxicity 6
- Uses 7
- References 8
- Books 9.1
- 9.2 Articles and chapters
- Websites 9.3
- External links 10
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' outer coats 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 plants flower, but some species have persistent foliage. Plants produce from one to 12 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 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.
The fruits are capsules that open longitudinally along the capsule wall between the partitions of the locule. The seeds are black, and have a rounded shape.
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, such as Allium paradoxum, the bulbils replace some or all the flowers. The umbels are subtended by noticeable spathe bracts, which are commonly fused and normally have around three veins.
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.
Many of the species of Allium have been used as food items throughout their ranges. There are several poisonous species that are somewhat similar in appearance (e.g. in North America, death camas, Toxicoscordion venenosum), but none of these has the distinctive scent of onions or garlic.
With over 800 species Allium, the sole genus in the Allieae tribe, is one of the largest monocotyledonous genera., but the precise taxonomy of Allium is poorly understood, with incorrect descriptions being widespread. However, the genus has been shown to be monophyletic, containing three major clades, although some proposed subgenera are not.
Allium includes a number of taxonomic groupings previously considered separate genera (Caloscordum Herb., Milula Prain and Nectaroscordum Lindl.) Allium spicatum had 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.
When Linnaeus formerly described the genus Allium in his 
Linnaeus originally grouped his 30 species into three alliances, e.g. Foliis caulinis planis. Since then many attempts have been made to divide the growing number of recognised species into infrageneric subgroupings, initially as sections, and then as subgenera further divided into sections. The modern era of phylogenetic analysis dates to 2006 when Friesen described a new classification with 15 subgenera, 72 sections and about 780 species based on the nuclear ribosomal gene ITSnuclear ribosomal ITS. Some of the subgenera correspond to the once separate genera (Caloscordum, Milula, Nectaroscordum) included in Gilliesieae.
Subsequent molecular phylogenetic studies have shown 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 major evolutionary lineages correspond to the three major clades. Lineage One (the oldest) with three subgenera are predominantly bulbous, the second, with five subgenera and the third with seven subgenera contain both bulbous and rhizomatous taxa.
The three lineages and fifteen subgenera represent the classification scheme of Friesen et al. (2006) and Li (2010). (number of sections/number of species)
- Nectaroscordum (Lindl.) Asch. et Graebn Type: Allium siculum (1/3)
- Microscordum (Maxim.) N. Friesen Type: Allium monanthum (1/1)
- Amerallium Traub Type: Allium canadense (12/135)
- Caloscordum (Herb.) R. M. Fritsch Type: Allium neriniflorum (1/3)
- Anguinum (G. Don ex Koch) N. Friesen Type: Allium victorialis (1/12)
- Porphyroprason (Ekberg) R. M. Fritsch Type: Allium oreophilum (1/1)
- Vvedenskya (Kamelin) R. M. Fritsch Type: Allium kujukense (1/1)
- Melanocrommyum (Webb et Berth.) Rouy Type: Allium nigrum (15/140)
- Butomissa (Salisb.) N. Friesen Type: Allium ramosum (2/4)
- Cyathophora R. M. Fritsch Type: Allium cyathophorum (3/5)
- Rhizirideum (G. Don ex Koch) Wendelbo s.s Type: Allium senescens (5/37)
- Allium L. Type: Allium sativum (15/300)
- Reticulatobulbosa (Kamelin) N. Friesen Type: Allium lineare (5/80)
- Polyprason Radic Type: Allium moschatum (4/50)
- Cepa (Mill.) Radic ́ Type: Allium cepa (5/30)
- Allium acuminatum — tapertip onion, Hooker's onion
- Allium allegheniense — Appalachian onion
- Allium ampeloprasum — (broadleaf) wild leek
- Allium anceps — twinleaf onion
- Allium angulosum — mouse garlic
- Allium aflatunense — flowering onion
- Allium atrorubens — dark red onion
- Allium caeruleum — blue globe onion
- Allium campanulatum — dusky onion
- Allium canadense — Canadian garlic
- Allium cepa — onion, garden onion, bulb onion, common onion
- Allium cernuum — nodding onion
- Allium chinense — Chinese onion, Chinese scallion, Japanese scallion, Oriental onion
- Allium cuthbertii — striped garlic
- Allium fistulosum — Welsh onion
- Allium galanthum
- Allium giganteum — giant onion
- Allium hollandicum — flowering onion
- Allium libani — Lebanese onion
- Allium neapolitanum — white garlic
- Allium nevii — Nevius' garlic
- Allium nigrum — black garlic
- Allium oleraceum — field garlic
- Allium oschaninii — shallot
- Allium paradoxum — few-flowered garlic
- Allium ramosum — fragrant garlic
- Allium sativum — garlic
- Allium schoenoprasum — chives
- Allium scorodoprasum — sand leek
- Allium siculum — Mediterranean bells, Sicilian honey garlic
- Allium sieberianum — Schult.f.
- Allium stipitatum — Persian shallot
- Allium textile — prairie onion
- Allium tricoccum — wild leek, ramp
- Allium triquetrum — three-cornered leek, triquetous garlic
- Allium tuncelianum — Tunceli garlic, Ovacik garlic
- Allium tuberosum — Chinese chives
- Allium ursinum — ramsons, buckrams, wild garlic, broad-leaved garlic, wood garlic, bear's garlic
- Allium vineale — crow garlic, wild garlic
Distribution and habitat
The majority of Allium species are native to the  A single known exception, Allium dregeanum occurs in the southern hemisphere (South Africa). There are two centres of diversity, a major one from the Mediterranean Basin to Central Asia and Pakistan, while a minor one is found in western North 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 (e.g., A. ursinum), or even in swamps or water.
Various Allium species are used as food plants by the larvae of the leek moth and onion fly as well as 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.
Many Allium species have been harvested through human history, but only about a dozen are still economically important today as crops or garden vegetables.
Many Allium species and hybrids are cultivated as ornamentals. These include A. cristophii and A. giganteum, which are used as herbaceous 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 produce spherical umbels on single stalks in spring and summer, 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. The hybrid cultivars 'Beau Regard', 'Gladiator', and 'Globemaster' have gained the Royal Horticultural Society's Award of Garden Merit.
Dogs and cats are very susceptible to poisoning after the consumption of certain species.
The genus includes many economically important species. These include onions (A. cepa), French shallots (A. oschaninii), leeks (A. ampeloprasum), scallions (various Allium species), and herbs such as garlic (A. sativum) and chives (A. schoenoprasum). Some have been used as traditional medicines.
- (Garlic). Hand-coloured engravingAllium sativum1793 illustration from William Woodville: "Medical botany", London, James Phillips, 1793, Vol. 3, Plate 168:
- Kew World Checklist of Selected Plant Families
- Quattrocchi 1999, vol. 1 p. 91.
- Eric Block (2010). Garlic and Other Alliums: The Lore and the Science. Royal Society of Chemistry.
- Dilys Davies (1992). Alliums: The Ornamental Onions. Timber Press.
- 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
- AlliumThe Plant List, for genus
- Hirschegger, Pablo; Jaške, Jernej; Trontelj, Peter; Bohanec, Borut (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.
- Allium In: Index Nominum Genericorum. In: Regnum Vegetabile (see External links below).
- Chase, M.W.; Reveal, J.L. & Fay, M.F. (2009), "A subfamilial classification for the expanded asparagalean families Amaryllidaceae, Asparagaceae and Xanthorrhoeaceae", Botanical Journal of the Linnean Society 161 (2): 132–136,
- James L. Brewster, "Onions and Other Alliums" (Wallingford: CABI Publishing, 2008)
- 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)
- Frodin, David G. (2004). "History and concepts of big plant genera". Taxon 53 (3): 753–776.
- "Allium in Flora of China @". Efloras.org. Retrieved 2012-12-11.
- "Allium in Flora of North America @". Efloras.org. Retrieved 2012-12-11.
- Peterson, R.P. 1982. A Field Guide to Edible Wild Plants: Eastern and central North America. Houghton Mifflin, Boston.
- Gibbons, E. 1962. Stalking the wild asparagus. David McKay, New York.
- Li et al. 2010.
- Friesen et al 2000.
- Linnaeus 1753, Allium I pp. 294–301.
- Linnaeus Sexual System 2015.
- Linnaeus 1753, Hexandria monogynia I pp. 285–332.
- Friesen, Fritsch & Blattner 2006.
- Sykorova 2006.
- Nguyen et al 2008.
- Gualtiero Simonetti (1990). Stanley Schuler, ed. Simon & Schuster's Guide to Herbs and Spices. Simon & Schuster, Inc.
- 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).
- 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
- "RHS Plant Selector Allium 'Beau Regard' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2012-12-11.
- "RHS Plant Selector Allium 'Gladiator' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2012-12-11.
- "RHS Plant Selector Allium 'Globemaster' AGM / RHS Gardening". Apps.rhs.org.uk. Retrieved 2012-12-11.
- Cope RB. Toxicology Brief: Allium species poisoning in dogs and cats. Veterinary Medicine 2005
- Block, Eric (2009). Garlic and other alliums : the lore and the science. Cambridge: Royal Society of Chemistry.
- Brewster, J. L. (2008). Onions and Other Alliums. CABI Publishing.
- Davies, D. (1992). Alliums: The Ornamental Onions. Timber Press.
- see Species Plantarum
- Rabinowitch, H. D.; Currah, L. (2002). Allium Crop Sciences: Recent Advances. CABI Publishing.
- Quattrocchi, Umberto (1999). CRC world dictionary of plant names: common names, scientific names, eponyms, synonyms, and etymology. Boca Raton, FL: CRC Press.
- Woodward, P. (1996). Garlic and Friends: The History, Growth and Use of Edible Alliums. Hyland House.
Articles and chapters
- Enrico Banfi, Gabriele Galasso & Adriano Soldano. Notes on systematics and taxonomy for the Italian vascular flora. 2. Atti Soc. it. Sci. nat. Museo civ. Stor. nat. Milano, 152 (II): 85-106, Novembre 2011
- Choi, Hyeok Jae; Giussani, Liliana M.; Jang, Chang Gee; Oh, Byoung Un; Cota-Sánchez, J. Hugo (June 2012). "Systematics of disjunct northeastern Asian and northern North American Allium (Amaryllidaceae)". Botany 90 (6): 491–508.
- . Volume 95, Number 8, December, 1997TAG Theoretical and Applied 'Genetics (G. Don ex Koch) Wendelbo according to dot blot hybridization with randomly amplified DNA probes Rhizirideum L. subgenus AlliumJ. G. Dubouzet, K. Shinoda and N. Murata. Phylogeny of
- . Volume 95, Number 8, December, 1997TAG Theoretical and Applied Genetics verified with GISH and RAPD. Melanocrommyum subgenus AlliumN. Friesen, R. Fritsch and K. Bachmann. Hybrid origin of some ornamentals of
- Friesen, Nikolai; Fritsch, Reinhard M.; Pollner, Sven; Blattner, Frank R. (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.
- Friesen, N; Fritsch, RM; Blattner, Frank R (2006). (Alliaceae) based on nuclear ribosomal DNA ITS sequences"Allium"Phylogeny and new intrageneric classification of (PDF). Aliso 22: 372–395. Retrieved 13 October 2015.
- Fritsch, RM; Blattner, FR; Gurushidze, M (2010). (Webb & Berthel) Rouy (Alliaceae) based on molecular and morphological characters"Melanocrommyum L. subg. Allium"New classification of . Phyton 49: 145–220. Retrieved 13 October 2015.
- Fritsch, RM; Friesen, N. Evolution, domestication and taxonomy., in Rabinowitch & Currah (2003, pp. 5–30)
- İpek, Meryem; İpek, Ahmet; SIMON, Philipp W. (2014). "Testing the utility of matK and ITS DNA regions for discrimination of Allium species". Turkish Journal of Botany 38: 203–212.
- Huang, De-Qing; Yang, Jing-Tian; Zhou, Chun-Jing; Zhou, Song-Dong; He, Xing-Jin (21 December 2013). "Phylogenetic reappraisal of Allium subgenus Cyathophora (Amaryllidaceae) and related taxa, with a proposal of two new sections". Journal of Plant Research 127 (2): 275–286.
- Li, R. J.; Shang, Z. Y.; Cui, T. C.; Xu, J. M. (1996). "Studies on karyotypes and phylogenetic relationship of Allium sect. Caloscordum (Liliaceae) from China". Acta Phytotax. Sin. 34: 288–295. [In Chinese.]
- Li, Q.-Q.; Zhou, S.-D.; He, X.-J.; Yu, Y.; Zhang, Y.-C.; Wei, X.-Q. (21 October 2010). "Phylogeny and biogeography of Allium (Amaryllidaceae: Allieae) based on nuclear ribosomal internal transcribed spacer and chloroplast rps16 sequences, focusing on the inclusion of species endemic to China". Annals of Botany 106 (5): 709–733.
- Nguyen, Nhu H.; Driscoll, Heather E.; Specht, Chelsea D. (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.
- Volume 110 Issue 1–2, Pages 103–109, 1999Feddes Repertorium (Alliaceae) II. Bromatorrhiza and subgenus Amerallium subgenus AlliumA. Samoylov, N. Friesen, S. Pollner, P. Hanelt. Use of chloroplast DNA polymorphisms for the phylogenetic study of
- Seregin, Alexey P.; Anačkov, Goran; Friesen, Nikolai (May 2015). "Molecular and morphological revision of the Allium saxatile group (Amaryllidaceae): geographical isolation as the driving force of underestimated speciation". Botanical Journal of the Linnean Society 178 (1): 67–101.
- Sykorova, E.; Fajkus, J.; Meznikova, M.; Lim, K. Y.; Neplechova, K.; Blattner, F. R.; Chase, M. W.; Leitch, A. R. (1 June 2006). "Minisatellite telomeres occur in the family Alliaceae but are lost in Allium". American Journal of Botany 93 (6): 814–823.
- Wheeler, E. J.; Mashayekhi, S.; McNeal, D. W.; Columbus, J. T.; Pires, J. C. (26 March 2013). "Molecular systematics of Allium subgenus Amerallium (Amaryllidaceae) in North America". American Journal of Botany 100 (4): 701–711.
- Zubaida Yousaf; Zabta Khan Shinwari; Rizwana ALEEM Qureshi; Mir Ajab Khan; Syed Shahinshah Gilani (2004). L., be resolved through some numerical techniques?"Allium"Can complexity of the genus (PDF). Pak. J. Bot. 36 (3): 487–501. Retrieved 28 January 2015.
- "Linnaeus Sexual System". CronkLab. Biodiversity Research Centre, University of British Columbia. Retrieved 26 January 2015.
Pacific Bulb Society: Allium
- Pacific Bulb Society: Rhizomatous Alliums
- "WCSP". World Checklist of Selected Plant Families. (enter "Allium" in search box).
- Allium At:Index Nominum Genericorum At:References At:NMNH Department of Botany
- Bloomsta.com Florist Community