''. The
genus Allium (alliums) is characterised by
herbaceous geophyte perennials with true
bulbs, some of which are borne on
rhizomes, and an
onion or
garlic odor and flavor. The bulbs are solitary or clustered and
tunicate and the plants are perennialized by the bulbs reforming annually from the base of the old bulbs, or are produced on the ends of
rhizomes or, in a few species, at the ends of
stolons. The seeds are black, and have a rounded shape. The
terete or flattened flowering scapes are normally persistent. The inflorescences are
umbels, in which the outside flowers bloom first and flowering progresses to the inside. Some species produce
bulbils within the umbels, and in some species, such as
Allium paradoxum, the bulbils replace some or all the flowers. The umbels are subtended by noticeable spathe bracts, which are commonly fused and normally have around three veins. Some bulbous alliums increase by forming little bulbs or "offsets" around the old one, as well as by
seed. Several species can form many bulbils in the flowerhead; in the so-called "
tree onion" or Egyptian onion (
A. ×
proliferum) the bulbils are few, but large enough to be
pickled. Many of the species of
Allium have been used as food items throughout their ranges. There are several unrelated species that are somewhat similar in appearance to alliums but are poisonous (e.g. in North America, death camas,
Toxicoscordion venenosum), but none of these has the distinctive scent of onions or garlic. ==Taxonomy==