Probably better known as Allium cepa proliferum, this species is now recognized as being of hybrid origin between Allium cepa and Allium fistulosum and has been renamed accordingly[].

Common Name: Tree Onion

General Information

Allium × proliferum is a herbaceous, perennial plant producing up to 10 leaves around 30cm long and a scape that can be up to 100cm tall from an underground bulb. The plant divides fairly freely, forming in time a cluster of bulbs[]. The scape of this species produces few if any flowers, instead it produces a cluster of small bulbs which can either be eaten or used for propagation.
The tree onion is often grown in gardens as a curiosity and food plant, producing edible bulbils, leaves and bulbs. The plant also has a range of medicinal and other uses.

Known Hazards

There have been cases of poisoning caused by the consumption, in large quantities and by some mammals, of this plant. Dogs seem to be particularly susceptible[].

Botanical References

Range

The plant is of hybrid origin and is not known as a truly wild species.

Habitat

Not known in the wild.

Properties

Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Bulb
Height	1.20 m
Pollinators	Bees, Insects
Cultivation Status	Wild

Cultivation Details

Prefers a sunny position in a light well-drained soil[] but succeeds in most soils that are in good condition[]. Tolerates a pH in the range 4.5 to 8.3.
The bulbs should be planted fairly deeply[].
Plants rarely if ever produce seed, instead the flowering head is comprised of a number of small onions or bulbils[, ]. This species is completely sterile and does not form fertile seeds[]. Plants are propagated by means of the bulbils or by dividing the main bulb that grows underground[]. By no means a heavily productive plant, though the bulbils are very well flavoured and the plant is fairly easily grown[]. Its main problem is that slugs seem to be attracted to it and can eat to death even well-established plants[].
The plant is said to be immune to onion root fly[].
Members of this genus are rarely if ever troubled by browsing deer[].

Edible Uses

The plant forms small bulbs at the top of the flowering stem, these can be eaten raw or cooked[, ]. They have a strong onion flavour and are often used as pickled onions or added to salads[].
As long as the bulbils are dried properly at harvest time, they store well[].

Bulb - raw or cooked. The bulb can be up to 4cm in diameter and has a strong onion flavour[]. Chopped into slices, it makes a good addition to salads and can also be used as a vegetable or as a flavouring in cooked foods[].

Leaves - raw or cooked. A strong onion flavour, it makes a nice flavouring in salads though it should not be harvested in quantity because this would reduce the yield of bulbils[]. The leaves are produced from late autumn, though we have found that harvesting them at this time will often encourage diseases such as mildew[].

Medicinal

Although rarely used specifically as a medicinal herb, the onion has a wide range of beneficial actions on the body and when eaten (especially raw) on a regular basis will promote the general health of the body.

The bulb is anthelmintic, anti-inflammatory, antiseptic, antispasmodic, carminative, diuretic, expectorant, febrifuge, hypoglycaemic, hypotensive, lithontripic, stomachic and tonic[, , ]. When used regularly in the diet it offsets tendencies towards angina, arteriosclerosis and heart attack[]. It is also useful in preventing oral infection and tooth decay[]. Baked onions can be used as a poultice to remove pus from sores[].
Fresh onion juice is a very useful first aid treatment for bee and wasp stings, bites, grazes or fungal skin complaints[, ]. When warmed the juice can be dropped into the ear to treat earache[]. It also aids the formation of scar tissue on wounds, thus speeding up the healing process, and has been used as a cosmetic to remove freckles[].

Agroforestry Uses:

The growing plant is said to repel insects and moles[].
Allium species usually grow well with most plants, especially roses, carrots, beet and chamomile, but they inhibit the growth of legumes[, , ]. They are, in general, bad companions for alfalfa - each species negatively affecting the other[].
Members of this genus are rarely if ever troubled by browsing deer[].

Other Uses

The juice of the plant is used as a moth repellent and can also be rubbed onto the skin to repel insects[].

The plant juice can be used as a rust preventative on metals and as a polish for copper and glass[].

A yellow-brown dye is obtained from the skins of the bulbs[, ].

Onion juice rubbed into the skin is said to promote the growth of hair and to be a remedy for baldness[]. It is also used as a cosmetic to get rid of freckles[].

The growing plant is said to repel insects and moles[]. A spray made by pouring enough boiling water to cover 1kg of chopped unpeeled onions is said to increase the resistance of other plants to diseases and parasites[].

Propagation

Harvest bulbils in late summer and replant immediately or store them in a cool dry frost-free place and plant them out in late winter or early spring.
Division of the bulbs after the leaves die down in late summer.