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Allium cepa aggregatum - G.Don.

Potato Onion

Author	G.Don.	Botanical references	1
Family	Alliaceae	Genus	Allium
Synonyms
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[76].
Range	Not known in wild.
Habitat	Not known in wild.
Edibility Rating	4 (1-5)	Medicinal Rating	3 (1-5)

Physical Characteristics

Bulb growing to 1.2m.

The plant prefers light (sandy) and medium (loamy) soils and requires well-drained soil. The plant prefers acid, neutral and basic (alkaline) soils and can grow in very alkaline soil. It cannot grow in the shade. It requires moist soil.

Habitats

Cultivated Beds;

Cultivars: (as above except)
'Potato Onion'
'Red Potato Onion'
'White Potato Onion'
'Yelow Potato Onion'

Edible Uses

Edible Parts: Flowers; Leaves; Root.

Bulb - raw or cooked[4, 33]. A nice onion flavour, when chopped up finely they make a nice addition to salads and can also be used as a cooked vegetable or as a flavouring in cooked foods[K]. Some of the cultivars are considered to be gourmet onions[183]. Leaves - raw or cooked. A strong onion flavour[K]. Flowers - raw. Used as a garnish on salads. The flowers are somewhat dry and are less pleasant than many other species[K].

Medicinal Uses

Anthelmintic; Antiinflammatory; Antiseptic; Antispasmodic; Carminative; Diuretic; Expectorant; Febrifuge; Hypoglycaemic; Hypotensive; Lithontripic; Skin; Stomachic; Tonic.

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[4, 7, 21]. When used regularly in the diet it offsets tendencies towards angina, arteriosclerosis and heart attack[254]. It is also useful in preventing oral infection and tooth decay[254]. Baked onions can be used as a poultice to remove pus from sores[254]. Fresh onion juice is a very useful first aid treatment for bee and wasp stings, bites, grazes or fungal skin complaints[7, 201]. When warmed the juice can be dropped into the ear to treat earache[254]. 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[7].

Other Uses

Cosmetic; Dye; Hair; Polish; Repellent; Rust.

The juice of the plant is used as a moth repellent and can also be rubbed onto the skin to repel insects[7]. The plant juice can be used as a rust preventative on metals and as a polish for copper and glass[7]. A yellow-brown dye is obtained from the skins of the bulbs[141, 168]. Onion juice rubbed into the skin is said to promote the growth of hair and to be a remedy for baldness[7]. It is also used as a cosmetic to get rid of freckles[7]. The growing plant is said to repel insects and moles[201]. 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[201].

Cultivation details

Prefers a sunny sheltered position in a light well-drained fertile soil[1] but tolerates most soils. Tolerates a pH in the range 4.5 to 8.3. The potato onion was at one time fairly widely grown as a vegetable, but it has now fallen into virtual disuse[16]. There are still some named forms available[183]. This is a genuinely perennial form of A. cepa, the bulb grows deeper in the soil and divides to produce a number of underground bulbs each year in much the same way as shallots. Large bulbs divide to form 5 - 15 bulbs whilst smaller bulbs grow into one large bulb[160]. According to one report, the bulbs should be planted fairly deeply[1], whilst another report says that they should be planted just below soil level[4]. Onions grow well with most plants, especially roses, carrots, beet and chamomile, but they inhibit the growth of legumes[18, 20, 54]. This plant is a bad companion for alfalfa, each species negatively affecting the other[201]. Members of this genus are rarely if ever troubled by browsing deer[233].

Propagation

Seed - sow spring in a cold frame. Seed is seldom produced by this plant[4]. Division in late summer. Harvest the bulbs as the foliage dies down and store them in a cool place. In areas with mild winters the bulbs are traditionally replanted on the shortest day of the year, but in colder areas it is best to wait until late winter or even early spring[4]. Plant the bulbs only just below the soil surface[4].

Cultivars

'Potato Onion'

Each large bulb divides under the ground to form 8 - 12 smaller ones about 20mm in diameter - when planted these will each produce 1 - 2 larger bulbs up to 10cm in diameter in the following year[183]. Slightly more pungent than normal onoins, they can also be left in the ground for mild cooking onions later in the season[183].

'Red Potato Onion'

The medium-size bulbs have a pale-pink flesh and are up to 10cm in diameter, they are flavourful, yet not strong, and keep very well for up to 12 months[183]. A very hardy plant[183].

'White Potato Onion'

Similar to other potato onions, but producing smaller bulbs to 25mm in diameter[183]. It divides underground to form clusters of up to 15 bulbs[183]. The flavour becomes stronger in hot weather[183]. The plants are used as bunching onions in the spring and autumn, or the bulbs can be prepared like pearl onions[183].

'Yelow Potato Onion'

The medium-size bulbs are up to 10cm in diameter, they are flavourful, yet not strong, and keep well for 8 - 12 months[183]. A widely adapted, hardy plant, it is resistant to drought and pink root[183].

Links

This plant is also mentioned in the following PFAF articles: Allium Species - the Perennial Onions.

Permaculture.info Details of this plant in the Permaculture.info project, a community plant and permaculture database.

References

[K] Ken Fern
Notes from observations, tasting etc at Plants For A Future and on field trips.

[1] F. Chittendon. RHS Dictionary of Plants plus Supplement. 1956 Oxford University Press 1951
Comprehensive listing of species and how to grow them. Somewhat outdated, it has been replaces in 1992 by a new dictionary (see [200]).

[4] Grieve. A Modern Herbal. Penguin 1984 ISBN 0-14-046-440-9
Not so modern (1930's?) but lots of information, mainly temperate plants.

[7] Chiej. R. Encyclopaedia of Medicinal Plants. MacDonald 1984 ISBN 0-356-10541-5
Covers plants growing in Europe. Also gives other interesting information on the plants. Good photographs.

[16] Simons. New Vegetable Growers Handbook. Penguin 1977 ISBN 0-14-046-050-0
A good guide to growing vegetables in temperate areas, not entirely organic.

[18] Philbrick H. and Gregg R. B. Companion Plants. Watkins 1979
Details of beneficial and antagonistic relationships between neighbouring plants.

[20] Riotte. L. Companion Planting for Successful Gardening. Garden Way, Vermont, USA. 1978 ISBN 0-88266-064-0
Fairly good.

[21] Lust. J. The Herb Book. Bantam books 1983 ISBN 0-553-23827-2
Lots of information tightly crammed into a fairly small book.

[33] Organ. J. Rare Vegetables for Garden and Table. Faber 1960
Unusual vegetables that can be grown outdoors in Britain. A good guide.

[54] Hatfield. A. W. How to Enjoy your Weeds. Frederick Muller Ltd 1977 ISBN 0-584-10141-4
Interesting reading.

[76] Cooper. M. and Johnson. A. Poisonous Plants in Britain and their Effects on Animals and Man. HMSO 1984 ISBN 0112425291
Concentrates mainly on the effects of poisonous plants to livestock.

[141] Carruthers. S. P. (Editor) Alternative Enterprises for Agriculture in the UK. Centre for Agricultural Strategy, Univ. of Reading 1986 ISBN 0704909820
Some suggested alternative commercial crops for Britain. Readable. Produced by a University study group.

[160] Natural Food Institute, Wonder Crops. 1987. 0
Fascinating reading, this is an annual publication. Some reports do seem somewhat exaggerated though.

[168] Grae. I. Nature's Colors - Dyes from Plants. MacMillan Publishing Co. New York. 1974 ISBN 0-02-544950-8
A very good and readable book on dyeing.

[183] Facciola. S. Cornucopia - A Source Book of Edible Plants. Kampong Publications 1990 ISBN 0-9628087-0-9
Excellent. Contains a very wide range of conventional and unconventional food plants (including tropical) and where they can be obtained (mainly N. American nurseries but also research institutes and a lot of other nurseries from around the world.

[201] Allardice.P. A - Z of Companion Planting. Cassell Publishers Ltd. 1993 ISBN 0-304-34324-2
A well produced and very readable book.

[233] Thomas. G. S. Perennial Garden Plants J. M. Dent & Sons, London. 1990 ISBN 0 460 86048 8
A concise guide to a wide range of perennials. Lots of cultivation guides, very little on plant uses.

[254] Chevallier. A. The Encyclopedia of Medicinal Plants Dorling Kindersley. London 1996 ISBN 9-780751-303148
An excellent guide to over 500 of the more well known medicinal herbs from around the world.

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