description
Allium cepa is a biennial plant but it is usually grown as an annual. It is
part of the Amaryllidaceae family. Modern varieties typically grow to a
height of 15 to 45 cm (6 to 18 in) with blueish-green leaves that grow
alternately in a flattened, fan-shaped swathe. The leaves fleshy, hollow and
cylindrical, with one flattened side. They are at their broadest about a
quarter of the way up the stalk beyond which they taper towards a blunt tip. The base
of each leaf is a flattened (usually white) sheath that grows out of a basal
disc. From the underside of the disc, a bundle of fibrous roots extends for
a short way into the soil. As the onion plant matures, food reserves begin to
accumulate in the leaf bases and the bulb of the onion will swell.
In the autumn the leaves die back and the outer scales of the bulb become
dry and brittle, and this is the time at which the crop is normally
harvested. If left in the soil over winter, the growing point in the middle
of the bulb begins to develop in the spring. New leaves appear and a long,
stout, hollow stem expands, topped by a bract protecting a developing
inflorescence. The flower-head takes the form of a globular umbel of white
flowers with parts in sixes. The seeds are glossy black and triangular in
cross section.
common names & nomenclature
Onion is from Anglo-French union; Old French oignon meaning "onion" (formerly also
oingnon), and directly from Latin unionem (nominative unio), a colloquial
rustic Roman for "a kind of onion”.
Also known as:
onion, bulb onion, common onion
