The tree onion (''Allium'' × ''proliferum'') is a
perennial plant similar to the
common onion (''A. cepa''), but with a cluster of bulblets where a normal onion would have flowers. Tree onions are also known as topsetting onions, walking onions, or Egyptian onions. Genomic evidence has conclusively shown that they are a
diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
hybrid of the
shallot and the
Welsh onion (''A. fistulosum'').
[ ] However, some sources may still treat the tree onion as ''A. cepa'' var. ''proliferum'' or ''A. cepa'' Proliferum Group.
Tree onion bulblets will sprout and grow while still on the original stalk. The bulblets are usually marble-sized, between 0.5 cm to 3 cm in diameter. They may bend down under the weight of the new growth and take root some distance from the parent plant, giving rise to the name "walking onion". It has been postulated that the name "Egyptian onion" derived from
Romani people bringing tree onions to Europe from the Indian subcontinent.
The phenomenon of forming bulblets (
bulbils) instead of flowers is also seen in top-setting
garlic
Garlic (''Allium sativum'') is a species of bulbous flowering plant in the genus ''Allium''. Its close relatives include the onion, shallot, leek, chive, Allium fistulosum, Welsh onion and Allium chinense, Chinese onion. It is native to South A ...
and other alliums, which sometimes may also be referred to as top onions or tree onions.
Also known as turfed stone leek, it may be cultivated commercially and for foliage.
It is described as a shallot which can be grown in tropical conditions.
Many tree onions are very strong flavoured, although some cultivars are relatively mild and sweet.
The underground bulbs are particularly tough-skinned and pungent,
and can be quite elongate, like
leek
The leek is a vegetable, a cultivar of ''Allium ampeloprasum'', the broadleaf wild leek ( syn. ''Allium porrum''). The edible part of the plant is a bundle of leaf sheaths that is sometimes erroneously called a stem or stalk. The genus ''Alli ...
s,
or in some types may form bulbs up to 5 cm across.
Young plants may be used as
scallions in the spring, and the bulblets may be used in cooking similarly to regular onions, or preserved by
pickling.
Culinary use
Japan
The plant is known as in Japan. Considered a specialty of the
Hiroshima Prefecture
is a Prefectures of Japan, prefecture of Japan located in the Chūgoku region of Honshu. Hiroshima Prefecture has a population of 2,811,410 (1 June 2019) and has a geographic area of 8,479 km² (3,274 sq mi). Hiroshima Prefecture borders Okayama ...
, it is used in local cooking similar to other scallions.
Korea
In Korea, ''Allium'' × ''proliferum'' along with ''
A. fistulosum'' is called ''pa'' (, "scallion"), while common
onions are called ''yangpa'' (, "Western scallion"). While ''A.'' × ''proliferum'' is called ''jjokpa'' (), ''A. fistulosum'' is called either ''
daepa'' (, "big scallion") or ''
silpa
''Allium fistulosum'', the Welsh onion, also commonly called bunching onion, long green onion, Japanese bunching onion, and spring onion, is a species of perennial plant, often considered to be a kind of scallion.
The species is very similar ...
'' (, "thread scallion") depending on the size. Unlike ''daepa'' and ''silpa'', which are usually used as a spice, herb, or garnish, ''jjokpa'' is often used as the main ingredient of various scallion dishes in
Korean cuisine
Korean cuisine has evolved through centuries of social and political change. Originating from ancient agricultural and nomadic traditions in Korea and southern Manchuria, Korean cuisine reflects a complex interaction of the natural envi ...
. Common dishes made with ''jjokpa'' include ''
pajeon'' (scallion pancakes) and ''
pa-kimchi'' (scallion kimchi).
File:Haemulpajeon.jpg, '' Haemul- pajeon'' (scallion pancake with seafood)
File:Scallion kimchi.jpg, '' Pa-kimchi'' (scallion kimchi)
Gallery
Image:Allium cepa2.jpg, Egyptian onions
Image:Sint Jansui (Allium fistulosum var. bulbifera).jpg, Tree onion
Image:Egyptian Tree Onion, Walking Onion, Topset Onion (Allium cepa var. proliferum).jpg, Growing in a garden
See also
*
List of'' Allium'' species
*
Scallion
References
{{taxonbar, from=Q41794154
proliferum
Interspecific plant hybrids
Korean vegetables
Onions
Perennial vegetables