''Allium'' is a large genus of

monocotyledon Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are flowering plants whose seeds contain only one embryonic leaf, or cotyledon. A monocot taxon has been in use for several decades, but with various ranks ...

ous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family

Amaryllidaceae The Amaryllidaceae are a family of herbaceous, mainly perennial and bulbous (rarely rhizomatous) flowering plants in the monocot order Asparagales. The family takes its name from the genus '' Amaryllis'' and is commonly known as the amaryl ...

and among the largest plant genera in the world. Many of the species are edible, and some have a long history of cultivation and human consumption as a vegetable including the

onion An onion (''Allium cepa'' , from Latin ), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classifie ...

garlic Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus '' Allium''. Its close relatives include the onion, shallot, leek, chives, Welsh onion, and Chinese onion. Garlic is native to central and south Asia, str ...

scallions Scallions (also known as green onions and spring onions) are edible vegetables of various species in the genus ''Allium''. Scallions generally have a milder taste than most onions. Their close relatives include garlic, shallots, leeks, chive ...

shallots The shallot is a cultivar group 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 difference was to ...

, leeks, and

chives Chives, scientific name ''Allium schoenoprasum'', is a species of flowering plant in the family Amaryllidaceae. A perennial plant, ''A. schoenoprasum'' is widespread in nature across much of Eurasia and North America. It is the only spe ...

, with onions being the second most grown vegetable globally after tomatoes as of 2023. ''Allium'' species occur in

temperate climate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ra ...

s of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

, 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 . The

flower Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...

s form an

umbel UMBEL (Upper Mapping and Binding Exchange Layer) is a logically organized knowledge graph of 34,000 concepts and entity types that can be used in information science for relating information from disparate sources to one another. It was retired ...

at the top of a leafless stalk. The

bulb In botany, a bulb is a short underground stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs duri ...

s 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.

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

first described the genus ''Allium'' in 1753. 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 International_Code_of_Zoological_Nomenclature, 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 spe ...

for the genus is ''

Allium sativum Garlic (''Allium sativum'') is a species of bulbous flowering plants in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chives, Allium fistulosum, Welsh onion, and Allium chinense, Chinese onion. Garlic is native to ...

'' which means "cultivated garlic".''Allium'' In: Index Nominum Genericorum. In:

Regnum Vegetabile The International Association for Plant Taxonomy (IAPT) is an organization established to promote an understanding of plant biodiversity, facilitate international communication of research between botanists, and oversee matters of uniformity and ...

(see ' below). The decision to include a species in the genus ''Allium'' is taxonomically difficult, and

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

boundaries are unclear. Estimates of the number of species are as low as 260,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. and as high as 979. In the APG III classification system, ''Allium'' is placed in the family

, subfamily

Allioideae Allioideae is a subfamily of monocot flowering plants in the family Amaryllidaceae, order Asparagales. It was formerly treated as a separate family, Alliaceae. The subfamily name is derived from the generic name of the type genus, ''Allium''. ...

(formerly the family Alliaceae). In some of the older

classification systems Classification is the activity of assigning objects to some pre-existing classes or categories. This is distinct from the task of establishing the classes themselves (for example through cluster analysis). Examples include diagnostic tests, identif ...

, ''Allium'' was placed in

Liliaceae The lily family, Liliaceae, consists of about 15 genera and 610 species of flowering plants within the order Liliales. They are monocotyledonous, perennial, herbaceous, often bulbous geophytes. Plants in this family have evolved with a fai ...

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies have shown this

circumscription Circumscription may refer to: * Circumscribed circle * Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthr ...

of Liliaceae is not

monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...

. Various ''Allium'' species have been cultivated from the earliest times. About a dozen species are economically important as

crops A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, fibre, or fuel. When plants of the same species a ...

, or garden

vegetables Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including flowers, fruits, ...

, and an increasing number of species are important as ornamental plants. Plants of the genus produce chemical compounds, mostly derived from

cysteine Cysteine (; symbol Cys or C) is a semiessential proteinogenic amino acid with the chemical formula, formula . The thiol side chain in cysteine enables the formation of Disulfide, disulfide bonds, and often participates in enzymatic reactions as ...

sulfoxide In organic chemistry, a sulfoxide, also called a sulphoxide, is an organosulfur compound containing a sulfinyl () functional group attached to two carbon atoms. It is a polar functional group. Sulfoxides are oxidized derivatives of sulfides. E ...

s, 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 The sulfate or sulphate ion is a polyatomic anion with the empirical formula . Salts, acid derivatives, and peroxides of sulfate are widely used in industry. Sulfates occur widely in everyday life. Sulfates are salts of sulfuric acid and many ...

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.

Description

The

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

''Allium'' (alliums) is characterised by

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

geophyte A storage organ is a part of a plant specifically modified for storage of energy (generally in the form of carbohydrates) or water. Storage organs often grow underground, where they are better protected from attack by herbivores. Plants that have ...

perennials In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...

with true

bulbs In botany, a bulb is a short underground stem with fleshy leaves or leaf basesBell, A.D. 1997. ''Plant form: an illustrated guide to flowering plant morphology''. Oxford University Press, Oxford, U.K. that function as food storage organs during ...

, some of which are borne on

rhizomes In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

, and an

odor and flavor. The bulbs are solitary or clustered and

tunicate Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping 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

or, in a few species, at the ends of

stolons In biology, a stolon ( from Latin '' stolō'', genitive ''stolōnis'' – "branch"), also known as a runner, is a horizontal connection between parts of an organism. It may be part of the organism, or of its skeleton. Typically, animal stolons ar ...

. 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

tepal A tepal is one of the outer parts of a flower (collectively the perianth). The term is used when these parts cannot easily be classified as either sepals or petals. This may be because the parts of the perianth are undifferentiated (i.e. of very ...

s produced in two whorls. The flowers have one

style Style, or styles may refer to: Film and television * ''Style'' (2001 film), a Hindi film starring Sharman Joshi, Riya Sen, Sahil Khan and Shilpi Mudgal * ''Style'' (2002 film), a Tamil drama film * ''Style'' (2004 film), a Burmese film * '' ...

and six epipetalous

stamen The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s; the

anther The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filament ...

s and

pollen Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...

can vary in color depending on the species. The

ovaries The ovary () is a gonad in the female reproductive system that produces ova; when released, an ovum travels through the fallopian tube/oviduct into the uterus. There is an ovary on the left and the right side of the body. The ovaries are endocr ...

are superior, and three-lobed with three

locule A locule (: locules) or loculus (; : loculi) is a small cavity or compartment within an organ or part of an organism (animal, plant, or fungus). In angiosperms (flowering plants), the term ''locule'' usually refers to a chamber within an ovary ...

s. 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 Terete is a term in botany used to describe a cross section (geometry), cross section that is circular, or like a distorted circle, with a single surface wrapping around it.Lichen Vocabulary, Lichens of North America Information, Sylvia and S ...

or flattened flowering scapes are normally persistent. The inflorescences are

s, in which the outside flowers bloom first and flowering progresses to the inside. Some species produce

bulbils A bulbil (also referred to as a bulbel, bulblet, and/or pup) is a small, young plant that is reproduced vegetatively from axillary buds on the parent plant's stem or in place of a flower on an inflorescence. These young plants are clones of the ...

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 In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be Sowing, sown, which may include seed and husk or tuber. Seeds ...

. Several species can form many bulbils in the flowerhead; in the so-called "

tree onion The tree onion (''Allium'' × ''proliferum'') is a perennial plant similar to the common onion (''A. cepa''), but with a cluster of bulblets where a normal onion would have flowers. Tree onions are also known as topsetting onions, walking ...

" or Egyptian onion (''A.'' × ''proliferum'') the bulbils are few, but large enough to be

pickled Pickling is the process of preserving or extending the shelf life of food by either anaerobic fermentation in brine or immersion in vinegar. The pickling procedure typically affects the food's texture and flavor. The resulting food is called ...

. Many of the species of ''Allium'' have been used as food items throughout their ranges. There are several unrelated species that are somewhat similar in appearance to Alliums but are poisonous (e.g. in North America, death camas, ''

Toxicoscordion venenosum ''Toxicoscordion venenosum'', with the common names death camas and meadow death camas, is a species of flowering plant in the family Melanthiaceae. It is named for its well known toxic qualities, with both its common names and its scientific nam ...

''), 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

tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

s of

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

(

). New species continue to be described and ''Allium'' is one of the largest monocotyledonous genera, but the precise

taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...

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

, containing three major

clades In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...

, although some proposed subgenera are not. Some progress is being made using molecular phylogenetic methods, and the

internal transcribed spacer Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript. ...

(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 In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...

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 ' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genus, genera. It is the first work to consistently apply binomial nomenclature ...

'' (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 Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl (botany), whorl of a flower; it consists ...

) 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 In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

dates to 1996. In 2006 Friesen, Fritsch, and Blattner described a new classification with 15

subgenera In biology, a subgenus ( subgenera) is a taxonomic rank directly below genus. In the International Code of Zoological Nomenclature, a subgeneric name can be used independently or included in a species name, in parentheses, placed between the ge ...

, 56

sections Section, Sectioning, or Sectioned may refer to: Arts, entertainment and media * Section (music), a complete, but not independent, musical idea * Section (typography), a subdivision, especially of a chapter, in books and documents ** Section sig ...

, 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 (messenger RNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to fo ...

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

s. Some of the subgenera correspond to the once separate genera (''Caloscordum'', ''Milula'', ''Nectaroscordum'') included in the

Gilliesieae Gilliesieae is a tribe (biology), tribe of herbaceous geophyte plants belonging to the subfamily Allioideae of the Amaryllis family (biology), family (Amaryllidaceae). Described in 1826, it contains fifteen genera and about eighty species. It ha ...

. 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 Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies have shown the 2006 classification is a considerable improvement over previous classifications, but some of its subgenera and sections are probably not

. 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 ''Allium ampeloprasum'' is a member of the onion genus ''Allium''. The wild plant is commonly known as wild leek or broadleaf wild leek. Its native range is southern Europe to southwestern Asia and North Africa, but it is cultivated in many othe ...

'', although sampling was not sufficient to test the monophyly of the section. The major evolutionary lineages 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 here represent the classification schemes of Friesen ''et al.'' (2006) and Li (2010), and subsequent additional species and revisions. ;Evolutionary lines and subgenera (number of sections/number of species) * First evolutionary line (3 subgenera) *# '' Nectaroscordum'' (Lindl.) Asch. et Graebn Type: ''

Allium siculum ''Allium siculum'' ( syn. ''Nectaroscordum siculum''), known as honey garlic, Sicilian honey lily, Sicilian honey garlic, or Mediterranean bells, is a European and Turkish species of plant in the genus ''Allium''. It is native to the regions arou ...

'' (1/3) Mediterranean bells, Sicilian honey garlic *# '' Microscordum'' (Maxim.) N. Friesen Type: ''

Allium monanthum ''Allium monanthum'', the Korean wild chive, is a spring vegetable with minuscule bulbous roots that have a mild onion flavor and found in the woodlands of Korea, Japan, northeastern Russia (Primorye), and northeastern China (Hebei, Heilongjiang ...

'' (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 other re ...

'' (12/135) * Second evolutionary line (5 subgenera) *# '' 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 Webb may refer to: Places Antarctica *Webb Glacier (South Georgia) *Webb Glacier (Victoria Land) * Webb Névé, Victoria Land, the névé at the head of Seafarer Glacier * Webb Nunataks, a group of nunataks in the Neptune Range * Webb Peak (disa ...

et Berthel.) Rouy Type: ''

'' (20/160) * Third evolutionary line (7 subgenera) *# '' Butomissa'' (Salisb.) N. Friesen Type: '' Allium ramosum'' (2/4) fragrant garlic *# '' Cyathophora'' R. M. Fritsch Type: '' Allium cyathophorum'' (3/5) *# '' Rhizirideum'' (G. Don ex Koch) Wendelbo s.s Type: '' Allium senescens'' (5/37) *# ''

Allium ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' L. Type: ''

'' (15/300) garlic *# '' Reticulatobulbosa'' (Kamelin) N. Friesen Type: '' Allium lineare'' (5/80) *# '' Polyprason'' Radic Type: '' Allium moschatum'' (4/50) *# '' Cepa'' (Mill.) Radic ́ Type: ''

Allium cepa An onion (''Allium cepa'' , from Latin ), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus ''Allium''. The shallot is a botanical variety of the onion which was classified ...

'' (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 In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

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.

Proposed infrageneric groups

Names from * '' Allium sect. Acanthoprason'' Wendelbo * ''

Allium subsect. Acuminatae ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ownbey ex Traub * ''

Allium sect. Amerallium ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Traub * '' Allium sect. Anguinum'' G. Don * '' Allium sect. Brevispatha'' Vals. * ''

Allium sect. Briseis ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Stearn * ''

Allium sect. Bromatorrhiza ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ekberg * '' Allium sect. Caloscordum'' Baker * ''

Allium subsect. Campanulatae ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ownbey ex Traub * '' Allium sect. Caulorhizideum'' Traub * ''

Allium subsect. Cepa ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Stearn * ''

Allium subsect. Cernuae ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Rchb. * ''

Allium sect. Codonoprasum ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ekberg * ''

Allium sect. Falcatifolia ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' N. Friesen * ''

Allium subsect. Falcifoliae ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ownbey ex Traub * ''

Allium sect. Halpostemon ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Boiss. * '' Allium sect. Haneltia'' F.O. Khass. * '' Allium sect. Lophioprason'' Traub. * '' Allium subg. Melanocrommyon'' (Webb & Berthel.) Rouy * ''

Allium subsect. Mexicana ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Traub * ''

Allium sect. Molium ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' G. Don ex W.D.J. Koch * '' Allium sect. Multicaulea'' F.O. Khass. & Yengal. * '' Allium sect. Oreiprason'' F. Herm. * '' Allium sect. Petroprason'' F. Herm. * '' Allium subg. Polyprason'' Radic * ''

Allium sect. Porrum ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' G. Don * ''

Allium sect. Rhiziridium ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' G. Don ex W.D.J. Koch * '' Allium sect. Rhophetoprason'' Traub * ''

Allium subsect. Sanbornae ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Ownbey ex Traub * ''

Allium sect. Schoenoprasum ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' Dumort. * ''

Allium sect. Scorodon ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' * ''

Allium sect. Unicaulea ''Allium'' is a large genus of monocotyledonous flowering plants with around 1000 accepted species, making ''Allium'' the largest genus in the family Amaryllidaceae and among the largest plant genera in the world. Many of the species are edible, ...

'' F.O. Khass.

Etymology

Some sources refer to Greek ἀλέω (aleo, to avoid) due to the odor of garlic.

Distribution and habitat

The majority of ''Allium'' species are native to the

, being spread throughout the

holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...

region, from dry

subtropics The subtropical zones or subtropics are geographical and climate zones immediately to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately ...

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'' occurs in the Southern Hemisphere (South Africa). There are two centres of diversity, a major one from the Mediterranean Basin to

Central Asia Central Asia is a region of Asia consisting of Kazakhstan, Kyrgyzstan, Tajikistan, Turkmenistan, and Uzbekistan. The countries as a group are also colloquially referred to as the "-stans" as all have names ending with the Persian language, Pers ...

and

Pakistan Pakistan, officially the Islamic Republic of Pakistan, is a country in South Asia. It is the List of countries and dependencies by population, fifth-most populous country, with a population of over 241.5 million, having the Islam by country# ...

, while a minor one is found in western North America. The genus is especially diverse in the

eastern Mediterranean The Eastern Mediterranean is a loosely delimited region comprising the easternmost portion of the Mediterranean Sea, and well as the adjoining land—often defined as the countries around the Levantine Sea. It includes the southern half of Turkey ...

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 (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of the

leek moth The leek moth or onion leaf miner (''Acrolepiopsis assectella'') is a species of moth of family Acrolepiidae (formerly Glyphipterigidae) and the genus ''Acrolepiopsis''. The species is native to Europe and Siberia, but is also found in North Amer ...

and onion fly as well as other

Lepidoptera Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...

including

cabbage moth The cabbage moth (''Mamestra brassicae'') is primarily known as a pest that is responsible for severe crop damage of a wide variety of plant species. The common name, cabbage moth, is a misnomer as the species feeds on many fruits, vegetables, ...

common swift The common swift (''Apus apus'') is a medium-sized bird, superficially similar to the barn swallow or Common house martin, house martin but somewhat larger, though not stemming from those passerine species, being in the order Apodiformes. The re ...

moth (recorded on garlic), garden dart moth,

large yellow underwing The large yellow underwing (''Noctua pronuba'') is a moth, the type species for the family Noctuidae. It is an abundant species throughout the Palearctic realm, one of the most common and most familiar moths of the region. In some years the speci ...

moth,

nutmeg Nutmeg is the seed, or the ground spice derived from the seed, of several tree species of the genus '' Myristica''; fragrant nutmeg or true nutmeg ('' M. fragrans'') is a dark-leaved evergreen tree cultivated for two spices derived from its fru ...

moth,

setaceous Hebrew character The setaceous Hebrew character (''Xestia c-nigrum'') is a moth of the family Noctuidae. The species was first described by Carl Linnaeus in his 1758 10th edition of ''Systema Naturae''. It is found in the Palearctic realm. It is a common specie ...

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 Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

level. This remarkable variation was noted in the discussion of the evolution of

junk DNA Junk DNA (non-functional DNA) is a DNA sequence that has no known biological function. Most organisms have some junk DNA in their genomes—mostly pseudogenes and fragments of transposons and viruses—but it is possible that some organ ...

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 reconc ...

, a "reality check for anyone who thinks they have come up with a universal function for junk DNA".

Genome size Genome size is the total amount of DNA contained within one copy of a single complete genome. It is typically measured in terms of mass in picograms (trillionths or 10−12 of a gram, abbreviated pg) or less frequently in daltons, or as the tot ...

s vary between 7.5 Gb in '' A. schoenoprasum'' and 30.9 Gb in '' A. ursinum'', both of which are

diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...

Telomere

The unusual telomeric sequence of 'Allium cepa' was discovered and cytologically validated to be CTCGGTTATGGG A bioinformatics method for detecting this unique telomere sequence was demonstrated using SERF de novo Genome Analysis

Cultivation

Many ''Allium'' species have been harvested through human history, but only about a dozen are still economically important today as crops or garden

vegetable Vegetables are edible parts of plants that are consumed by humans or other animals as food. This original meaning is still commonly used, and is applied to plants collectively to refer to all edible plant matter, including edible flower, flo ...

Ornamental

Many ''Allium'' species and hybrids are cultivated as ornamentals.

Anthony Huxley Anthony Julian Huxley (2 December 1920 – 26 December 1992) was a British botanist and writer. An elected council member of the Royal Horticultural Society, he became its vice president in 1991. He edited '' Amateur Gardening'' from 1967 to 19 ...

, 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 generally defined as geography, geographical boundaries, imposed either by features such as oceans and terrain, or by polity, political entities such as governments, sovereign states, federated states, and other administrative divisio ...

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 The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. It includes the full range of cultivated p ...

(H4).''RHS Plant Finder 2009–2010'', p. 68, 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

weed A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...

s.Lloyd, Christopher & Rice, Graham, (1991). ''Garden Flowers From Seed'', p. 45, Viking, The following cultivars, of uncertain or mixed parentage, have gained the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...

: *'Ambassador' *'Beau Regard' *'Gladiator' *'Globemaster' *'Michael H. Hoog' ( ''A. rosenorum'') *'Round 'n' Purple' *'Universe'

Toxicity

Dogs The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the gray wolf. Also called the domestic dog, it was selectively bred from a population of wolves during the Late Pleistocene by hunter-gatherers ...

and

cats The cat (''Felis catus''), also referred to as the domestic cat or house cat, is a small domesticated carnivorous mammal. It is the only domesticated species of the family Felidae. Advances in archaeology and genetics have shown that the ...

are very susceptible to poisoning after the consumption of certain species. Cattle have occasionally suffered onion toxicosis as well. Vegetables of the ''Allium'' genus can cause digestive disorders for human beings.

Uses

The genus includes many economically important species. These include

s (''A. cepa''), French shallots (''A. oschaninii''), leeks (''A. ampeloprasum''),

(''A. sativum''), and

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

s such as

(various ''Allium'' species) and

(''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 ''Allium ursinum'', known as wild garlic, ramsons, cowleekes, cows's leek, cowleek, buckrams, broad-leaved garlic, wood garlic, bear leek, Eurasian wild garlic or bear's garlic, is a bulbous perennial flowering plant in the amaryllis family, Ama ...

'') in Europe and ramps (''

Allium tricoccum ''Allium tricoccum'' (commonly known as ramps, ramson, wild leek, wood leek, or wild garlic) is a bulbous perennial flowering plant in the amaryllis family Amaryllidaceae. It is a North American species of wild onion or garlic found in eastern ...

'') in North America.

References

Sources

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Bibliography

Books

* * * * * * *

Chapters

* , in

Articles

* * * * * * * * * * * * * * * * n Chinese.* *
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
* * * * *

Websites

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DutchGrown: Alliums

Pacific Bulb Society: Allium
*
Pacific Bulb Society: Rhizomatous Alliums
*

External links

*
Allium
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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