Alliums

Alliums are a diverse genus of flowering plants in the Amaryllidaceae family, encompassing roughly 800 species. They include many cultivated vegetables such as onions (Allium cepa), garlic (Allium sativum), leeks (Allium porrum), and shallots (Allium cepa var. aggregatum), as well as numerous ornamental species and wild relatives. Alliums are native to temperate regions of the Northern Hemisphere and are grown worldwide for food, medicine, or ornamental value.

Most alliums form underground bulbs or bulbils and display a rosette of linear to hollow leaves. They produce an umbel of small, often fragrant flowers, typically with six tepals and six stamens, which can range in color from white and green to pink or purple. The sulfur-containing compounds released by damaged tissue are characteristic of the group and contribute to their distinctive aroma and taste.

Culinary use is extensive; bulbs and leaves are eaten fresh or cooked in a wide range of cuisines. In addition to flavor, many alliums have been used in traditional medicines; sulfur compounds such as allicin are associated with various effects, though evidence varies and should be interpreted cautiously.

Cultivation is adaptable to a range of soils and climates but generally requires well-drained soil and a sunny position. Bulbs may be planted in autumn or spring, depending on species; propagation can be by seed, bulb-offsets, or dividing clumps. Pests and diseases include onion maggots, thrips, white rot, and other fungal pathogens, and some species can naturalize or become invasive in suitable habitats.

Ornamental alliums, with globose flower heads, are popular in gardens for structure and late-spring interest, while edible species are valued for their storage and flavor in cooking.