Allium is a family/species of plants known as the onion family. The family has approx. 800 species. Almost all have been tested since the last 3000 years. Only a few are economically important. A specie can grow in various soils from dry, well-drained to moist. Most need sunshine but some grow in forests or swamps/water. Onions (A. cepa), leeks (A. ampeloprasum) and herbs such as garlic (A. sativum) and chives (A. schoenoprasum) are most popular.
Some species (such as the Welsh onion) develop thickened leaf-bases rather than bulbs. Allium species produce chemical compounds (mostly cysteine sulfoxide) with the onion odour and/or garlic taste. Some species produce spectacular flower balls. In most cases, both bulb and leafs are edible. Many alliums have leafs that usual dies before or while the plant flowers, but some species have persistent foliage, like leek and chives.