Onion
| Onion | |
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| Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Asparagales |
| Family: | Amaryllidaceae |
| Subfamily: | Allioideae |
| Tribe: | Allieae |
| Genus: | Allium |
| Species: | A. cepa |
| Binomial name | |
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Allium cepa L. |
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| Synonyms | |
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Species synonymy
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| Stereo image
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| Onion seeds have a very distinct shape. |
| Nutritional value per 100 g (3.5 oz) | |
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| Energy | 166 kJ (40 kcal) |
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9.34 g
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| Sugars | 4.24 g |
| Dietary fiber | 1.7 g |
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0.1 g
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1.1 g
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| Vitamins | |
| Thiamine (B1) |
(4%)
0.046 mg |
| Riboflavin (B2) |
(2%)
0.027 mg |
| Niacin (B3) |
(1%)
0.116 mg |
| Pantothenic acid (B5) |
(2%)
0.123 mg |
| Vitamin B6 |
(9%)
0.12 mg |
| Folate (B9) |
(5%)
19 μg |
| Vitamin C |
(9%)
7.4 mg |
| Minerals | |
| Calcium |
(2%)
23 mg |
| Iron |
(2%)
0.21 mg |
| Magnesium |
(3%)
10 mg |
| Manganese |
(6%)
0.129 mg |
| Phosphorus |
(4%)
29 mg |
| Potassium |
(3%)
146 mg |
| Zinc |
(2%)
0.17 mg |
| Other constituents | |
| Water | 89.11 g |
| Fluoride | 1.1 µg |
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| Percentages are roughly approximated using US recommendations for adults. Source: USDA Nutrient Database |
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The onion (Allium cepa L., from Latin cepa "onion"), also known as the bulb onion or common onion, is a vegetable and is the most widely cultivated species of the genus Allium.
This genus also contains several other species variously referred to as onions and cultivated for food, such as the Japanese bunching onion (Allium fistulosum), the tree onion (A. ×proliferum), and the Canada onion (Allium canadense). The name "" is applied to a number of Allium species, but A. cepa is exclusively known from cultivation. Its ancestral wild original form is not known, although escapes from cultivation have become established in some regions. The onion is most frequently a biennial or a perennial plant, but is usually treated as an annual and harvested in its first growing season.
The onion plant has a fan of hollow, bluish-green leaves and its bulb at the base of the plant begins to swell when a certain day-length is reached. In the autumn (or in spring, in the case of overwintering onions), the foliage dies down and the outer layers of the bulb become dry and brittle. The crop is harvested and dried and the onions are ready for use or storage. The crop is prone to attack by a number of pests and diseases, particularly the onion fly, the onion eelworm, and various fungi cause rotting. Some varieties of A. cepa, such as shallots and potato onions, produce multiple bulbs.
Onions are cultivated and used around the world. As a food item, they are usually served cooked, as a vegetable or part of a prepared savoury dish, but can also be eaten raw or used to make pickles or chutneys. They are pungent when chopped and contain certain chemical substances which irritate the eyes.
The onion plant (Allium cepa), also known as the bulb onion or common onion, is the most widely cultivated species of the genus Allium. It was first officially described by Carl Linnaeus in his 1753 work Species Plantarum. A number of synonyms have appeared in its taxonomic history:
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