''Allium'' is a genus of

monocotyledon Monocotyledons (), commonly referred to as monocots, ( Lilianae '' sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one ...

ous

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants t ...

s that includes hundreds of species, including the cultivated

onion An onion (''Allium cepa'' L., from Latin ''cepa'' meaning "onion"), 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 on ...

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 northeas ...

scallion Scallions (also known as spring onions or green onions) are vegetables derived from various species in the genus '' Allium''. Scallions generally have a milder taste than most onions and their close relatives include garlic, shallot, leek, c ...

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 ...

leek The leek is a vegetable, a cultivar of '' Allium ampeloprasum'', the broadleaf wild leek ( syn. ''Allium porrum''). The edible part of the plant is a bundle of leaf sheaths that is sometimes erroneously called a stem or stalk. The genus '' Al ...

, 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 specim ...

for the genus is ''

Allium sativum 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 northeastern ...

'' 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 A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydroponi ...

, or garden

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

, and an increasing number of species are important as

ornamental plants Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...

. 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 given ...

difficult, and

species In biology, a species is the basic unit of 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 the appropriat ...

boundaries are unclear. Estimates of the number of species are as low as 260, and as high as 979. ''Allium'' species occur in

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

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 as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

, 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 mechanis ...

s form an

umbel In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' "p ...

at the top of a leafless stalk. The

bulb In botany, a bulb is structurally a short 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 dur ...

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. Plants of the genus ''Allium'' produce chemical compounds, mostly derived from

cysteine Cysteine (symbol Cys or C; ) is a semiessential proteinogenic amino acid with the formula . The thiol side chain in cysteine often participates in enzymatic reactions as a nucleophile. When present as a deprotonated catalytic residue, some ...

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 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. 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 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 amaryllis f ...

, subfamily Allioideae (formerly the family Alliaceae). In some of the older

classification systems Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

, ''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 fair ...

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 of Liliaceae is not

monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gr ...

. ''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 Classification is a process related to categorization, the process in which ideas and objects are recognized, differentiated and understood. Classification is the grouping of related facts into classes. It may also refer to: Business, organizat ...

systems A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its environment, is described by its boundaries, structure and purpose and expresse ...

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 nom ...

''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 o ...

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 A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also widel ...

with true

bulbs In botany, a bulb is structurally a short 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 durin ...

, 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 ...

, and an

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 t ...

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. A small number of species have

tuberous Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing s ...

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 is a manner of doing or presenting things and may refer to: * Architectural style, the features that make a building or structure historically identifiable * Design, the process of creating something * Fashion, a prevailing mode of clothing ...

and six epipetalous

stamen The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the fila ...

s; the

anther The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10 Morphology and terminology A stamen typically consists of a stalk called the filam ...

s and

pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametop ...

can vary in color depending on the species. The

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

are superior, and three-lobed with three

locule A locule (plural locules) or loculus (plural loculi) (meaning "little place" in Latin) 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'' usu ...

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 that is circular, or like a distorted circle, with a single surface wrapping around it.Lichen Vocabulary, Lichens of North America Information, Sylvia and Stephen Sharnoff/ref> This is u ...

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 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 ''Alliu ...

'', 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 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 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 Allieae is a tribe of plants belonging to the subfamily Allioideae of the Amaryllis family (Amaryllidaceae). It comprises a single genus, ''Allium'', distributed in temperate zones of the Northern Hemisphere. Description Characterised by sim ...

, 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 usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confl ...

s of

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus Genus ( plural genera ) is a taxonomic rank used in the biological classifica ...

Allioideae (

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

taxonomy Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...

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 A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English te ...

, 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 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 genera. It is the first work to consistently apply binomial names and was the ...

'' (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 (; ) 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 of a flower; it consists of (one or more) '' pistils ...

) 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 (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

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

subgenera In biology, a subgenus (plural: 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 ...

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

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 ...

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

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

. 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'', 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'', 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 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'' (12/135) * Second evolutionary line *# ''Caloscordum'' (Herb.) R. M. Fritsch Type: '' Allium neriniflorum'' (1/3) *# ''Anguinum'' (G. Don ex Koch) N. Friesen Type: ''

Allium victorialis ''Allium victorialis'', commonly known as victory onion, Alpine leek, and Alpine broad-leaf allium is a broad-leaved Eurasian species of wild onion. It is a perennial of the Amaryllis family that occurs widely in mountainous regions of Europe an ...

'' (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 most often refers to James Webb Space Telescope which is named after James E. Webb, second Administrator of NASA. It may also refer to: Places Antarctica * Webb Glacier (South Georgia) * Webb Glacier (Victoria Land) * Webb Névé, Victor ...

et Berthel.) Rouy Type: '' Allium nigrum'' (20/160) * Third evolutionary line *# ''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'' 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'' (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.

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 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 35° nort ...

to the

boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

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 In biogeography, the Mediterranean Basin (; also known as the Mediterranean Region or sometimes Mediterranea) is the region of lands around the Mediterranean Sea that have mostly a Mediterranean climate, with mild to cool, rainy winters and wa ...

Central Asia Central Asia, also known as Middle Asia, is a region of Asia that stretches from the Caspian Sea in the west to western China and Mongolia in the east, and from Afghanistan and Iran in the south to Russia in the north. It includes the fo ...

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 Eastern Mediterranean is a loose definition of the eastern approximate half, or third, of the Mediterranean Sea, often defined as the countries around the Levantine Sea. It typically embraces all of that sea's coastal zones, referring to commun ...

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. ...

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 Ame ...

and onion fly as well as some

Lepidoptera Lepidoptera ( ) is an order of insects that includes butterflies and moths (both are called lepidopterans). About 180,000 species of the Lepidoptera are described, in 126 families and 46 superfamilies, 10 percent of the total described speci ...

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 moth (recorded on garlic),

garden dart The garden dart (''Euxoa nigricans'') is a moth of the family Noctuidae. It is distributed throughout much of the Palearctic. Temperate regions of Europe, Central Asia and North Asia, as well as the mountains of North Africa. Absent from pola ...

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

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. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectiv ...

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

junk DNA Non-coding DNA (ncDNA) sequences are components of an organism's DNA that do not encode protein sequences. Some non-coding DNA is transcribed into functional non-coding RNA molecules (e.g. transfer RNA, microRNA, piRNA, ribosomal RNA, and regula ...

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

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

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 borders ca ...

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 annual award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions. History The 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

weed A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...

s.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 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 (Nor ...

: *’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

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

(''A. sativum''), and

herb In general use, herbs are a widely distributed and widespread group of plants, excluding vegetables and other plants consumed for macronutrients, with savory or aromatic properties that are used for flavoring and garnishing food, for medicina ...

s 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 ''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 Amary ...

'') 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

* , 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
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Pacific Bulb Society: Rhizomatous Alliums

External links

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Allium
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Index Nominum Genericorum
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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