366 Handbook of herbs and spices
22.2 Leek.................................................................................................
22.2.1 Description, botany, origin and distribution
Description
Leeks known botanically as Allium ampeloprosum L. (Synon. A. porrum L.; A.
ampeloprasum var porrum (L.) Gay) are related to garlic and bear a resemblance to
onions, shallots and scallions. Common names in different languages are as follows:
Leek (English); jiu cong (Chinese); poireau, porreau (French); Porree (German);
porro, porretta (Italian); liiki (Japanese); luk porej (Russian); ajo porro, apuerro
(Spanish). Leeks look like large scallions, having a very small bulb and a long white
cylindrical stalk of superimposed layers that flows into green, tightly wrapped, flat
leaves. Cultivated leeks are usually about 30 cm in length and 5.0–8.5 cm in diameter,
and feature a fragrant flavour that is reminiscent of shallots but sweeter and more
subtle. Wild Leeks, known as ‘ramps’ are much smaller in size, but have a stronger,
more intense flavour (Anon. 2005a). With a more delicate and sweeter flavour than
onions, leeks add a subtle touch to recipes without overpowering the other flavours
that are present.
Botany
Leeks (Allium ampeloprasum) are members of the Alliaceae family. Other members
of the family include onion and garlic. The leek plant is a robust herbaceous biennial
that has been cultivated for centuries but has not been found wild. Leek plants
resemble large onion plants with flat leaves. Unlike onion and garlic, leeks do not
form bulbs or produce cloves. Leeks are made up of sheaths of basal leaves that can
be 15–25 cm long and 5 cm in diameter. The taste of leeks is milder than those of
onion and garlic. The leek is a tall, hardy, biennial with white, narrowly ovoid bulbs
and broad leaves. It resembles the green onion but is larger. Leek, is a tetraploid (2n
= 32). It differs mainly in its lesser tendency to form bulbs. Many cultivars selected
for long, white, edible bases and green tops, winter hardiness, and resistance to
bolting are available for cultivation. These cultivars differ from one another mainly
in length and diameter of the sheath part, leaf spacing, breadth and colour of leaf
blades, vigour and bolting, and resistance to cold.
Resistance to cold is of special importance where leeks are to be harvested throughout
the winter, while slowness to bolt permits a prolonged harvest period in the spring
(McCollum, 1976). Rather than forming a tight bulb such as the onion, the leek
produces a long cylinder of bundled leaf sheaths which are generally blanched by
pushing soil around them (trenching). They are often sold as small seedlings in flats
which are started early in greenhouses, to be set out as weather permits. Once established
in the garden leeks are hardy; many varieties can be left in the ground during the
winter to be harvested as needed (Anon., 2005a).
Origin and distribution
Randy Baker (1991) reported that the leek originated in Middle Asia, with secondary
centres of development and distribution in Western Asia and the Mediterranean countries.
The leek has been cultivated in Western Europe since the middle ages and found its
way to North America with early settlers from Europe. Leeks have been cultivated
from very early times (Silvertand, 1996). The garden leek was a popular vegetable in
the ancient Near East when the Egyptians built their pyramids, for example, that of