Onion (Allium cepa)

Onion (Allium cepa)
Onion (Allium cepa) is a plant species belonging to the Amaryllidaceae family. It is an herbaceous plant with a shallow, fibrous root system that branches out within the top 15–30 cm of the soil. At its base lies a thin, short, disc-like stem—the point of attachment for both the roots and the buds—from which a "pseudo-stem" (formed by overlapping leaf sheaths) rises; the portion of this structure located underground develops into a bulb.

A. cepa features small, cylindrical, hollow leaves that reach lengths of 50–70 cm. These leaves are green, taper to a pointed tip, and are attached to relatively short stalks.

Flower stalk emerges from the plant's growing point, reaching a length of 30–90 cm. At its apex, 50–200 individual flowers are arranged in an umbel (an umbrella-like cluster). Each flower consists of 5–6 white petals, 6 green or yellow stamens, a single pistil, and an ovary that is roughly triangular in shape.

The fruit is round with a blunt tip and contains 2–3 seeds. The seeds are somewhat flattened; they appear clear or white when immature and turn black upon reaching maturity. The plant is used medicinally to treat conditions such as fevers, diabetes, and coughs.

The plant contains quercetin, a potent antioxidant that acts as an agent to inhibit cancer cells. Other components include proteins, minerals, sulfur, anthocyanins, carbohydrates, and fiber.

TAXON

Kingdom: Plantae
Phylum: Tracheophyta
Subphylum: Angiospermae
Class: Liliopsida
Order: Asparagales
Family: Amaryllidaceae
Subfamily: Allioideae
Tribe: Allieae
Genus: Allium L. in Sp. Pl.: 300 (1753)
Subgenus: Cepa
Section: Cepa
Species: Allium cepa L. in Sp. Pl.: 300 (1753)

HOMOTYPIC SYNONYMS

Cepa esculenta Gray in Nat. Arr. Brit. Pl. 2: 183 (1821 publ. 1822)
Cepa vulgaris Garsault in Fig. Pl. Méd.: t. 207 (1764)
Kepa esculenta Raf. in Fl. Tellur. 2: 20 (1837)
Porrum cepa (L.) Rchb. in Fl. Germ. Excurs.: 110 (1830)

HETEROTYPIC SYNONYMS

Allium angolense Baker in Trans. Linn. Soc. London, Bot. 1: 262 (1878)
Allium aobanum Araki in Hokuriku J. Bot. 4: 45 (1955)
Allium ascalonicum Anon.
Allium ascalonicum var. condensum Millán in Darwiniana 10: 108 (1952)
Allium ascalonicum var. fertile Millán (1952)
Allium ascalonicum var. majus Gorrie in Miller's Dict. Gard.: 140 (1834)
Allium ascalonicum f. rotterianum Voss ex J.Becker in Handb. Gemüsebaues, ed. 2: 786 (1929)
Allium ascalonicum var. sterile Millán (1952)
Allium cepa var. aggregatum G.Don in Mem. Wern. Nat. Hist. Soc. 6: 27 (1827)
Allium cepa var. anglicum Alef. in Landw. Fl.: 300 (1866)
Allium cepa var. argenteum Alef. (1866)
Allium cepa var. bifolium Alef. (1866)
Allium cepa var. crinides Alef. (1866)
Allium cepa var. flandricum Alef. (1866)
Allium cepa var. globosum Alef. (1866)
Allium cepa var. hispanicum Alef. (1866)
Allium cepa var. jamesii Alef. (1866)
Allium cepa var. lisboanum Alef. (1866)
Allium cepa var. luteum Alef. (1866)
Allium cepa var. multiplicans L.H.Bailey in Princip. Veg. Gard.: 316 (1901)
Allium cepa var. portanum Alef. (1866)
Allium cepa var. praecox Alef. (1866)
Allium cepa var. roseum Alef. (1866)
Allium cepa var. sanguineum Alef. (1866)
Allium cepa var. solaninum Alef. (1866)
Allium cepa var. tripolitanum Alef. (1866)
Allium cepa f. viviparum Metzg. in Landw. Pflanzenk. 1: 257 (1841)
Allium cepa var. viviparum (Metzg.) Alef. (1866)
Allium cepaeum St.-Lag. in Ann. Soc. Bot. Lyon 7: 113 (1880)
Allium commune Noronha in Verh. Batav. Genootsch. Kunsten 5(4): 6 (1790)
Allium cumaria Buch.-Ham. ex Wall. in Numer. List: n.° 5072 (1831)
Allium esculentum Salisb. in Prodr. Stirp. Chap. Allerton: 235 (1796)
Allium fissile T.F.Grace in Bon Jard. 1797: 52 (1797)
Allium napus Pall. ex Kunth in Enum. Pl. 4: 395 (1843)
Allium nigritanum A.Chev. in Études Fl. Afr. Centr. Franç. 1: 319 (1913)
Allium pauciflorum Willd. ex Ledeb. in Fl. Ross. 4: 169 (1852)
Allium salota Dostál in Folia Mus. Rerum Nat. Bohemiae Occid., Bot. 21: 17 (1984)
Ascalonicum sativum P.Renault in Fl. Orne: 33 (1804)
Cepa alba P.Renault (1804)
Cepa esculenta var. hispanica Gray (1821 publ. 1822)
Cepa esculenta var. ramosa Gray (1821 publ. 1822)
Cepa esculenta var. rubra Gray (1821 publ. 1822)
Cepa pallens P.Renault (1804)
Cepa rubra P.Renault (1804)

PUBLICATIONS

Acevedo-Rodríguez, P. & Strong, M.T. (2012). Catalogue of seed plants of the West Indies. Smithsonian Contributions to Botany 98: 1-1192.

Baksh-Comeau, Y., Maharaj, S.S., Adams, C.D., Harris, S.A., Filer, D.L. & Hawthorne, W.D. (2016). An annotated checklist of the vascular plants of Trinidad and Tobago with analysis of vegetation types and botanical 'hotspots'. Phytotaxa 250: 1-431.

Boulos, L. (2005). Flora of Egypt 4: 1-617. Al Hadara Publishing, Cairo. Chang, C.S., Kim, H. & Chang, K.S. (2014). Provisional checklist of vascular plants for the Korea peninsula flora (KPF): 1-660. DESIGNPOST.

Danihelka, J. Chrtek, J. & Kaplan, Z. (2012). Checklist of vascular plants of the Czech Republic. Preslia. Casopsi Ceské Botanické Spolecnosti 84: 647-811.

Dar, G.H. & Govaerts, R.H.A. (2025). Flora of Kashmir Himalaya: Sind Valley 1: 1-606. Bishen Singh Mahendra Pal Singh, Dehradun, India.

Dimopoulos, P., Raus, T., Bergmeier, E., Constantinidis, T., Iatrou, G., Kokkini, S., Strid, A., & Tzanoudakis, D. (2013). Vascular plants of Greece. An annotated checklist: 1-372. Botanic gardens and botanical museum Berlin-Dahlem, Berlin and Hellenic botanical society, Athens.

Dobignard, D. & Chatelain, C. (2010). Index synonymique de la flore d'Afrique du nord 1: 1-455. Éditions des conservatoire et jardin botaniques, Genève.

Edwards, S., Demissew, S. & Hedberg, I. (eds.) (1997). Flora of Ethiopia and Eritrea 6: 1-586. The National Herbarium, Addis Ababa University, Ethiopia & The Department of Systematic Botany, Upps.

Espejo Serena, A. & López-Ferrari, A.R. (1993). Las Monocotiledóneas Mexicanas una Sinopsis Florística 1(1): 1-76. Consejo Nacional de la Flora de México, México D.F.

Flora of North America Editorial Committee (2002). Flora of North America North of Mexico 26: 1-723. Oxford University Press, New York, Oxford.

Fritsch, R. (2006). Personal Communication on Alliaceae 6 Germany.

Gilman, A.V. (2015). New flora of Vermont. Memoirs of the New York Botanical Garden 110: 1-614.

Govaerts, R. (1995). World Checklist of Seed Plants 1(1, 2): 1-483, 1-529. MIM, Deurne.

Hassler, M. & Muer, T. (2022). Flora Germanica: alle Farn- und Blütenpflanzen Deutschlands in Text und Bild 1: 1-864. Verlag Regionalkultur, Uberstadt-Weiher.

Jones, R.L. (2005). Plant life of Kentucky. An illustrated guide to the vascular flora: 1-833. The universitry press of Kentucky.

Jørgensen, P.M. & León-Yánes, S. (eds.) (1999). Catalogue of the Vascular Plants of Ecuador: 1-1181. Missouri Botanical Garden Press, St. Louis.

Lee, W.T. (1996). Lineamenta Florae Koreae: 1-1688. Soul T'ukpyolsi: Ak'ademi Sojok.

Maire, R. (1958). Flore de l'Afrique du Nord 5: 1-307. Paul Lechevalier, Paris.

Merkodovich, N.A. (ed.) (1941). Flora Uzbekistana 1: 1-566. Izd-va Akademii nauk Uzbekskoi SSR, Tashkent.

Mohlenbrock, R.H. (2014). Vascular Flora of Illinois. A Field Guide, ed. 4: 1-536. Southern Illinois University Press, Carbondale.

Nasir, E. (1975). Flora of Pakistan 83: 1-31. Department of Botany, University of Karachi, Karachi.

Nelson Sutherland, C.H. (2008). Catálogo de las plantes vasculares de Honduras. Espermatofitas: 1-1576. SERNA/Guaymuras, Tegucigalpa, Honduras.

Noltie, H.J. (1994). Flora of Bhutan 3(1): 1-456. Royal Botanic Gardens, Edinburgh.

Nurtjahya, E. & al. (2026). Flowering Plants of Bangka Island: Native and Introduced. Acta Botanica Hungarica 68: 127-156.

Ovczinnikov, P.N. (ed.) (1963). Flora Tadzhikskoi SSR 2: 1-454. Izd-vo Akademii nauk SSSR, Moskva.

Pachschwöl, C. & al. (eds.) (2024). Floristische Neufunde (509-620). Neilreichia 15: 127-248.

Pasha, M.K. & Uddin, S.B. (2013). Dictionary of plant names of Bangladesh, Vasc. Pl.: 1-434. Janokalyan Prokashani, Chittagong, Bangladesh.

Robertson, S.A. (1989). Flowering Plants of Seychelles: 1-327. Royal Botanic Gardens, Kew.

Sauerbier, H., Cabrera Calixto, F. & Muer, T. (2023). Flora Vascular de Canarias: 1-1514. Turquesa.

Singh, N.P. & Sanjappa, M. (eds.) (2006). Alliaceae, Liliaceae, Trilliaceae & Uvulariaceae. Fascicles of Flora of India 23: 1-134. Botanical Survey of India, New Delhi.

Smith, A.C. (1979). Flora Vitiensis Nova. A new flora for Fiji (Spermatophytes only) 1: 1-495. Pacific Tropical Botanical Garden, Lawai.

Smitinand, T. & Larsen, K. (eds.) (1978). Flora of Thailand 1: 1-694. The Forest Herbarium, National Park, Wildlife and Plant Conservation Department, Bangkok.

Stace, C. (2019). New Flora of the British Isles ed. 4: 1-1266. C & M Floristics.

Stalažs, A. (2024). List of vascular plants of Latvia (with Latvian names): 1-312. Dobele.

Townsend, C.C. & Guest, E. (eds.) (1985). Flora of Iraq 8: 1-440. Ministry of Agriculture & Agrarian Reform, Baghdad.

Zhengyi, W. & Raven, P.H. (eds.) (2000). Flora of China 24: 1-431. Missouri Botanical Garden Press, St. Louis.

Zuloaga, F.O. & Morrone, O. (eds.) (1996). Pteridophyta, Gymnospermae y Angiospermae (Monocotyledoneae). Catálogo de las Plantas Vasculares de la República Argentina 1: 1-323. Missouri Botanical Garden, St. Louis.

VERNACULAR NAME

Adi: Aying talab, Piyaj
Ahom: Pl-kat-nam
Apatani: Byaku
Arabic: بصل شائع - بصل
Armenian: Գլուխ սոխ
Assamese: Piyaj, Ponoru, Tikhnokondo
Awadhi: Piyaj
Bengali: পালান্ডু - পিম্যজা Palandu, Pimyaja
Bhojpuri: Piyaj
Bodo: Sambram gwja
Chinese (simplified): 洋葱 - 皮芽子 - 葱头
Chinese (traditional): 洋蔥
Czech: Cibule kuchyňská
Danish: Kepaløg
Dimasa: Samprang
Dogri: Gandha, Pyaaz
Dutch: Ui
English: Common onion, Garden onion, Bulb onion
Estonian: Harilik sibul, Söögisibul
Finnish: Ruokasipuli
French: Oignon
German: Gemeine Zwiebel
Gujarati: Dungali, Kando
Haryanvi: Piyaz
Hebrew: בצל הגינה
Hindi: कांडा - पलांडू - प्याज Kanda, Palandu, Pyaz
Hmar: Purunsen
Hungarian: Vöröshagyma
Indonesia: Bawang merah, Bawang bombay, Bawang, Berambang
Italian: Cipolla
Japanese: タマネギ
Java: Brambang, Berambang
Kachchhi: Dungari
Kannada: Eerulli, Neerulli, Ulligedde
Karbi: Harsun
Kashmiri: Gand
Khasi: Piat
Konkani: Kamdo, Piyav
Korean: 양파
Lithuanian: Valgomasis svogūnas
Maharashtra: Marathi
Maithili: Piauj
Malayalam: Bawang, Chuvannulli, Savala, Kappaulli, Ulli
Manipuri: Tilhou
Marathi: Kanda, Kandarpa, Palandu
Mishing: Dihlab
Mizo: Pu-rûn
Mundari: Pyaaj
Nagamese: Piaz
Nepali: प्याज Pyaaj
Norwegian: Kepaløk
Nyduka: Ayun
Odia: Palandu, Piaja
Otomí: Denchi
Palauan: Sebulias
Persian: Piyaz
Polish: Cebula, Czosnek cebula
Portuguese: Cebola
Punjabi: Gandha, Piaj
Rabha: Raysung
Rajasthani: Kaandau, Pyaaj
Romani: Porum
Russian: Лук репчатый
Sanskrit: Palandu, Sukandaka
Santali: Peyaz
Selete: Kwii
Sengwaketse: Kwii
Sindhi: Pieazu
Singpho: Shakau khyeng
Sinhala: ලොකු ළූණු
Slovak: Cibuľa kuchynská
Spanish: Cebolla, Cebolla cabezona
Swedish: Kepalök, Lök, Matlök
Tagalog: Sibuyas
Tai phake: Po lo
Tamil: உள்ளி - வெங்காயம் Ulli, Vengayam
Tangkhul: Tarui
Telugu: Nirulli
Thai: หอมใหญ่
Tibetan: Sgog-Btsong
Tswana: Segwere
Tulu: Neerulli
Turkish: Soğan
Turung: Shakau
Ukrainian: Цибуля городня
Urdu: کندا - پالنڈو Kanda, Palandu
Xinjiang Uygur: 皮芽子

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