Allium
Read about Allium in the Standard Cyclopedia of Horticulture
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Allium (ancient Latin name of garlic). Liliaceae. Bulbous plants, mostly cultivated in the open, but a few of them grown under glass as florist's flowers; and comprising also the onions and their allies. Leaves flat, channelled, or terete and hollow: fls. in a simple umbel, from a 1-2-lvd. usually scarious spathe; stamens and perianth segms. 6, the perianth parts distinct or nearly so, 1-nerved, and often becoming dry and persistent: style slender, the stigma either entire or parted.—Strong-scented plants, with fls. white, yellow, or in shades of purple and rose. There are 250-300 species in temperate parts of the northern hemisphere. Numbers of species, particularly the Asian, are frequently seen in botanic gardens and choice collections, but only A. Moly and A. neapolitanum are common in this country among the ornamental species, and no attempt is made to describe all the species here that are mentioned in garden literature. For the vegetable garden members of the genus, see Chives, Garlic, Leek, Onion,Shallot. In parts of the northeastern states Allium vineale is a bad weed; it has a slender scape sheathed below with hollow thread-shaped lvs., and greenish rose-colored fls. (or bulblets in the place of fls.). No special treatment is required by the alliums. Most of the cult. forms are hardy spring bloomers, and may be treated the same as other hardy border bulbs. Propagation is by offsets and by the bulblets in the umbel; also readily by seeds. A. Forgetii, Hort. Corolla pale yellow, spurred on the back. Peru. Index. acuminatum, 10. fimbriatum, 31. Sanbornii, 27. albopilosum, 14. fiatulosum, 3. sativum, 5. anceps, 33. Geyeri, 20. scaposum, 21. ascalonicum, 4. Hermettii, 9. Schoenoprasum, 1. attenuifolium, 28. haematochiton, 18.saenescens. 12. Bidwellae, 30. madidum, 22. serratum, 29. Bolanderi, 24. Moly, 7. sibiricum, 1. bulbellifera, 2. multiplicans. 2. stellatum, 26. Cepa, 2. neapolitunum, 9. tricoccum, 15. cernuum, 16. platycaule, 34. unifolium, 25. Cusickii. 23. Porrum, 6. validum, 17. Ellisii, 13. reticulatum, 19. victorialis, 8. falcifolium, 32. roseum, 11.
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Allium | ||||||||||||||||
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Crow Garlic (Allium vineale) flowerhead, showing sprouting bulbils | ||||||||||||||||
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Some important species: Allium acuminatum - tapertip onion
Allium anceps - twinleaf onion |
Allium is the onion genus, with about 1250 species, making it one of the largest plant genera in the world. They are perennial bulbous plants that produce chemical compounds that give them a characteristic onion or garlic taste and odor, and many are used as food plants. Allium is classified in family Alliaceae although some classifications have included it in the lily family (Liliaceae).
Allium species occur in temperate climates of the northern hemisphere, except for a few species occurring in Chile (as Allium juncifolium), Brazil (Allium sellovianum) or tropical Africa (Allium spathaceum). They can vary in height between 5 cm and 150 cm. The flowers form an umbel at the top of a leafless stalk. The bulbs vary in size between species, from very small (around 2–3 mm in diameter) to rather big (8–10 cm). Some species (such as Welsh onion, A. fistulosum) develop thickened leaf-bases rather than forming bulbs as such.
Most bulbous alliums increase by forming little bulbs or "offsets" around the old one, as well as by seed. Several species can form many bulbils (tiny bulbs) in the flowerhead; in the so-called "tree onion" (A. cepa Proliferum Group) the bulbils are few, but large enough to be used for pickling.
Members of the genus include many valued vegetables such as onions, shallots, leeks and herbs such as garlic and chives. A strong "oniony" odor is characteristic of the whole genus, but not all members are equally flavorful.
Some Allium species, including A. cristophii and A. giganteum, are used as border plants for their flowers, and their "architectural" qualities. Several hybrids have been bred, or selected, with rich purple flowers. Allium hollandicum 'Purple Sensation' is one of the most popular and has been given an Award of Garden Merit (H4). By contrast, other species (such as the invasive Allium triquetrum) can become troublesome garden weeds.
Various Allium species are used as food plants by the larvae of some Lepidoptera inclu ding Cabbage Moth, Common Swift moth (recorded on garlic), Garden Dart moth, Large Yellow Underwing moth, Nutmeg moth, Setaceous Hebrew Character moth, Turnip Moth and Schinia rosea, a moth which feeds exclusively on Allium spp.