''Allium'' is a genus of
monocotyledonous
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. They include all forbs (flowering plants without a woody stem), grasses and grass-like plants, a vast majority of ...
s that includes hundreds of species, including the cultivated
onion,
garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northe ...
,
scallion,
shallot,
leek, and
chives. The
generic name ''Allium'' is the Latin word for garlic,
[Gledhill, David (2008). "The Names of Plants". Cambridge University Press. (hardback), (paperback). pp 43] and the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...
for the genus is ''
Allium sativum'' which means "cultivated garlic".
[''Allium'' In: Index Nominum Genericorum. In: Regnum Vegetabile (see ''External links'' below).]
Carl Linnaeus
Carl Linnaeus (; 23 May 1707 – 10 January 1778), also known after his ennoblement in 1761 as Carl von Linné Blunt (2004), p. 171. (), was a Swedish botanist, zoologist, taxonomist, and physician who formalised binomial nomenclature, ...
first described the genus ''Allium'' in 1753. Some sources refer to Greek ἀλέω (aleo, to avoid) by reason of the smell of garlic.
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 decision to include a species in the genus ''Allium'' is
taxonomically
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are gi ...
difficult, and
species
In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...
boundaries are unclear. Estimates of the number of species are as low as 260,
and as high as 979.
''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
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanism ...
s 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'' and
leeks (''A. ampeloprasum'')) develop thickened leaf-bases rather than forming bulbs as such.
Plants of the genus ''Allium'' produce chemical compounds, mostly derived from
cysteine sulfoxides, 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. The characteristic ''Allium'' flavor depends on the sulfate content of the soil the plant grows in.][ In the rare occurrence of sulfur-free growth conditions, all ''Allium'' species completely lose their usual pungency.
In the APG III classification system, ''Allium'' is placed in the ]family
Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...
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.[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. ]
Description
The genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...
''Allium'' (alliums) is characterised by herbaceous geophyte perennials with true bulbs, some of which are borne on rhizomes, and an onion or garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northe ...
odor and flavor.
The bulbs are solitary or clustered and tunicate
A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ...
and the plants are perennialized by the bulbs reforming annually from the base of the old bulbs, 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, which are produced on scapes 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
''Allium paradoxum'', the few-flowered garlic or few-flowered leek, is an Asian species of wild onion in the Amaryllis family. It is native to mountainous regions of Iran, Caucasus, and Turkmenistan and invasive in Europe.
Description
''Allium ...
'', 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
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
. 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.
Taxonomy
With over 850 species ''Allium'' is the sole genus in the Allieae, one of four tribes of subfamily Allioideae ( Amaryllidaceae). New species continue to be described and ''Allium'' is one of the largest monocotyledonous genera, but the precise taxonomy of ''Allium'' is poorly understood, with incorrect descriptions being widespread. The difficulties arise from the fact that the genus displays considerable polymorphism and has adapted to a wide variety of habitats. Furthermore, traditional classifications had been based on homoplasious characteristics (the independent evolution of similar features in species of different lineages). However, the genus has been shown to be monophyletic, containing three major clades, although some proposed subgenera are not. Some progress is being made using molecular phylogenetic methods, and the internal transcribed spacer (ITS) region, including the 5.8S rDNA and the two spacers ITS1 and ITS2, is one of the more commonly used markers in the study of the differentiation of the ''Allium'' species.
''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''.
Phylogeny
History
When Linnaeus[ formerly described the genus ''Allium'' in his '' Species Plantarum'' (1753), there were thirty species with this name. He placed ''Allium'' in a grouping he referred to as ''Hexandria monogynia'' (i.e. six stamens and one pistil) containing 51 genera in all.
]
Subdivision
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. For a brief history, see Li ''et al.'' (2010) The modern era of phylogenetic analysis dates to 1996. In 2006 Friesen, Fritsch, and Blattner described a new classification with 15 subgenera, 56 sections, and about 780 species based on the nuclear
Nuclear may refer to:
Physics
Relating to the nucleus of the atom:
*Nuclear engineering
*Nuclear physics
*Nuclear power
*Nuclear reactor
*Nuclear weapon
*Nuclear medicine
*Radiation therapy
*Nuclear warfare
Mathematics
*Nuclear space
* Nuclear ...
ribosomal
Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to ...
gene
In biology, the word gene (from , ; "... Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a b ...
internal transcribed spacers. Some of the subgenera correspond to the once separate genera (''Caloscordum'', ''Milula'', ''Nectaroscordum'') included in the Gilliesieae. The terminology has varied with some authors subdividing subgenera into Sections and others Alliances. The term Alliance has also been used for subgroupings within species, ''e.g.'' ''Allium nigrum
''Allium nigrum'', common name black garlic, broad-leaved leek, or broadleaf garlic, is a Middle Eastern species of wild onion. It lacks the onion or garlic scent shared by most of the other species in the group. The species is native to Turke ...
'', and for subsections.
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. Meanwhile, the number of new species continued to increase, reaching 800 by 2009, and the pace of discovery has not decreased. Detailed studies have focused on a number of subgenera, including ''Amerallium''. ''Amerallium'' is strongly supported as monophyletic. Subgenus ''Melanocrommyum'' has also been the subject of considerable study (see below), while work on subgenus ''Allium'' has focussed on section ''Allium'', including '' Allium ampeloprasum'', although sampling was not sufficient to test the monophyly of the section.
The major evolutionary lineages
An evolutionary lineage is a temporal series of populations, organisms, cells, or genes connected by a continuous line of descent from ancestor to descendant.The Oxford English Dictionary defines biological lineage as "a sequence of species each of ...
or lines correspond to the three major clades. Line one (the oldest) with three subgenera is predominantly bulbous, the second, with five subgenera and the third with seven subgenera contain both bulbous and rhizomatous taxa.
Evolutionary lines and subgenera
The three evolutionary lineages and 15 subgenera represent the classification scheme of Friesen ''et al.'' (2006) and Li (2010). (number of sections/number of species)
* First evolutionary line
*# ''Nectaroscordum'' (Lindl.) Asch. et Graebn Type: '' Allium siculum'' (1/3) Mediterranean bells, Sicilian honey garlic
*# ''Microscordum'' (Maxim.) N. Friesen Type: '' Allium monanthum'' (1/1)
*# ''Amerallium'' Traub Type: ''Allium canadense
''Allium canadense'', the Canada onion, Canadian garlic, wild garlic, meadow garlic and wild onion is a perennial plant native to eastern North America from Texas to Florida to New Brunswick to Montana. The species is also cultivated in othe ...
'' (12/135)
* Second evolutionary line
*# ''Caloscordum'' (Herb.) R. M. Fritsch Type: ''Allium neriniflorum
''Allium neriniflorum'' is a species of wild onion native to Mongolia, the Zabaykalsky Krai region of Siberia, and northern China (Inner Mongolia, Hebei, Heilongjiang, Jilin, Liaoning). It grows on coastal sand dunes, wet meadows, hillsides, etc., ...
'' (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
''Allium kujukense'' is a species of onion in the genus ''Allium''. This species is in the family Amaryllidaceae and is endemic all over South-East Kazakhstan. This species has a bulbous geophyte
A storage organ is a part of a plant specifically ...
'' (1/1)
*# ''Melanocrommyum'' ( Webb et Berthel.
Sabin Berthelot (4 April 1794 – 10 November 1880) was a French naturalist and ethnologist. He was resident on the Canary Islands for part of his life, and co-authored ''L'Histoire Naturelle des Îles Canaries'' (1835–50) with Philip Barker We ...
) Rouy Type: ''Allium nigrum
''Allium nigrum'', common name black garlic, broad-leaved leek, or broadleaf garlic, is a Middle Eastern species of wild onion. It lacks the onion or garlic scent shared by most of the other species in the group. The species is native to Turke ...
'' (20/160)
* Third evolutionary line
*# ''Butomissa'' (Salisb.) N. Friesen Type: ''Allium ramosum
''Allium ramosum'', called Fragrant-flowered Garlic or Chinese chives is a northern Asian species of wild onion native to Kazakhstan, Mongolia, Siberia, the Russian Far East, and northern China (Gansu, Hebei, Heilongjiang, Jilin, Liaoning, Inner M ...
'' (2/4) fragrant garlic
*# ''Cyathophora'' R. M. Fritsch Type: '' Allium cyathophorum'' (3/5)
*# ''Rhizirideum'' (G. Don ex Koch) Wendelbo s.s Type: ''Allium senescens
''Allium senescens'', commonly called aging chive, German garlic, or broadleaf chives, is a species of flowering plant in the genus ''Allium'' (which includes all the ornamental and culinary onions and garlic).
Description
A bulbous herbaceous ...
'' (5/37)
*# ''Allium'' L. Type: '' Allium sativum'' (15/300) garlic
*# ''Reticulatobulbosa'' (Kamelin) N. Friesen Type: ''Allium lineare
''Allium lineare'' is a Eurasian species of wild onions with a wide range extending from France to Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered b ...
'' (5/80)
*# ''Polyprason'' Radic Type: ''Allium moschatum
''Allium moschatum'' is a Eurasian species of wild onion with a range extending from Spain to Iran.
''Allium moschatum'' is a bulb-forming perennial. Flowers are born in umbels on top of thin, wiry scapes rarely more than 15 cm tall; tepal ...
'' (4/50)
*# ''Cepa'' (Mill.) Radic ́ Type: '' Allium cepa'' (5/30) onion, garden onion, bulb onion, common onion
First evolutionary line
Although this lineage consists of three subgenera, nearly all the species are attributed to subgenus ''Amerallium'', the third largest subgenus of ''Allium''. The lineage is considered to represent the most ancient line within ''Allium'', and to be the only lineage that is purely bulbous, the other two having both bulbous and rhizomatous taxa. Within the lineage ''Amerallium'' is a sister group to the other two subgenera (''Microscordum''+''Nectaroscordum'').
Second evolutionary line
Nearly all the species in this lineage of five subgenera are accounted for by subgenus ''Melanocrommyum'', which is most closely associated with subgenera ''Vvedenskya'' and ''Porphyroprason'', phylogenetically. These three genera are late-branching whereas the remaining two subgenera, ''Caloscordum'' and ''Anguinum'', are early branching.
Third evolutionary line
The third evolutionary line contains the greatest number of sections (seven), and also the largest subgenus of the genus ''Allium'': subgenus ''Allium'', which includes the type species of the genus, ''Allium sativum''. This subgenus also contains the majority of the species in its lineage. Within the lineage, the phylogeny is complex. Two small subgenera, ''Butomissa'' and ''Cyathophora'' form a sister clade to the remaining five subgenera, with ''Butomissa'' as the first branching group. Amongst the remaining five subgenera, ''Rhizirideum'' forms a medium-sized subgenus that is the sister to the other four, larger, subgenera. This line may not be monophyletic.
Distribution and habitat
The majority of ''Allium'' species are native to the Northern Hemisphere, being spread throughout the holarctic region, from dry subtropics to the boreal zone, predominantly in Asia. Of the latter, 138 species occur in China, about a sixth of all ''Allium'' species, representing five subgenera. A few species are native to Africa and Central and South America. A single known exception, ''Allium dregeanum
''Allium dregeanum'' is the sole known species of ''Allium'' endemic to sub-Saharan Africa. It has also been described as the only ''Allium'' species endemic to the Southern Hemisphere, though some descriptions of the genus also include ''Allium ...
'' occurs in the Southern Hemisphere (South Africa). There are two centres of diversity
A center of origin is a geographical area where a group of organisms, either domesticated or wild, first developed its distinctive properties. They are also considered centers of diversity. Centers of origin were first identified in 1924 by Ni ...
, a major one from the Mediterranean Basin to Central Asia and Pakistan
Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
, while a minor one is found in western North America. The genus is especially diverse in the eastern Mediterranean.
Ecology
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 ]larva
A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle.
Th ...
e of the leek moth and onion fly
''Delia antiqua'', commonly known as the onion fly, is a cosmopolitan pest of crops. The larvae or maggots feed on onions, garlic, and other bulbous plants.
Morphology and biology
The onion fly has an ash-grey body and resembles a housefly. Th ...
[ 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.
]
Genetics
The genus Allium has very large variation between species in their genome size that is not accompanied by changes in ploidy level. This remarkable variation was noted in the discussion of the evolution of junk DNA and resulted in the Onion Test The onion test is a way of assessing the validity of an argument for a functional role for junk DNA. It relates to the paradox that would emerge if the majority of eukaryotic non-coding DNA were assumed to be functional and the difficulty of reconci ...
, a "reality check for anyone who thinks they have come up with a universal function for junk DNA". Genome sizes vary between 7.5 Gb in '' A. schoenoprasum'' and 30.9 Gb in '' A. ursinum'', both of which are diploid.
Cultivation
Many ''Allium'' species have been harvested through human history, but only about a dozen are still economically important today as crops or garden vegetables.
Ornamental
Many ''Allium'' species and hybrids are cultivated as ornamentals.[ 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. (set).] These include '' A. cristophii'' and '' A. giganteum'', which are used as border
Borders are usually defined as geographical boundaries, imposed either by features such as oceans and terrain, or by political entities such as governments, sovereign states, federated states, and other subnational entities. Political bo ...
plants for their ornamental flowers, and their "architectural" qualities.[Brickell, Christopher (Editor-in-chief),''The Royal Horticultural Society A–Z Encyclopedia of Garden Plants'', p.95, Dorling Kindersley, London, 1996, ] 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).[''RHS Plant Finder 2009–2010'', p68, Dorling Kindersley, London, 2009, ] 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.[Lloyd, Christopher & Rice, Graham, (1991) ''Garden Flowers From Seed'', p45, Viking, ]
The following cultivars, of uncertain or mixed parentage, have gained the Royal Horticultural Society's Award of Garden Merit:
*’Ambassador’
*’Beau Regard’
*’Gladiator’
*’Globemaster’
*'Michael H' Hoog' ( ''A. rosenorum'')
*’Round 'n' Purple’
*'Universe'
Toxicity
Dogs and cats are very susceptible to poisoning after the consumption of certain species.[Cope RB. Toxicology Brief: Allium species poisoning in dogs and cats. Veterinary Medicine 2005]
/ref>
Uses
The genus includes many economically important species. These include onions (''A. cepa''), French shallot
The shallot is a botanical variety (a cultivar) of the onion. Until 2010, the (French red) shallot was classified as a separate species, ''Allium ascalonicum''. The taxon was synonymized with ''Allium cepa'' (the common onion) in 2010, as the d ...
s (''A. oschaninii''), leeks (''A. ampeloprasum''), garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Welsh onion and Chinese onion. It is native to South Asia, Central Asia and northe ...
(''A. sativum''), and herbs such as scallions (various ''Allium'' species) and chives (''A. schoenoprasum''). Some have been used as traditional medicines.
This genus also includes species that are abundantly gathered from the wild such as wild garlic ('' Allium ursinum'') and ramps (''Allium tricoccum
''Allium tricoccum'' (commonly known as ramp, ramps, ramson, wild leek, wood leek, or wild garlic) is a North American species of wild onion or garlic widespread across eastern Canada and the eastern United States. Many of the common English n ...
'').
References
Bibliography
Books
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Chapters
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Articles
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* n Chinese.
N, or n, is the fourteenth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''en'' (pronounced ), plural ''ens''.
History
...
*
*
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
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Websites
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DutchGrown: Alliums
Pacific Bulb Society: Allium
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Pacific Bulb Society: Rhizomatous Alliums
External links
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Allium
A
Index Nominum Genericorum
A
A
Bloomsta.com Florist Community
Reinhard M. Fritsch. Checklist of ornamental ''Allium'' species and cultivars currently offered in the trade. 2015
{{Authority control
*Allium
Amaryllidaceae genera
Bulbous plants
Taxa named by Carl Linnaeus