Lettuce
| Lettuce | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Iceberg lettuce field in Northern Santa Barbara County
| ||||||||||||||
| Scientific classification | ||||||||||||||
| ||||||||||||||
| Lactuca sativa L. |
Lettuce is the common term for any plants of the genus Lactuca of the flowering plant family Asteraceae (or, alternatively, Compositae), and especially refers to plants of the commercially important species Lactuca sativa. The term lettuce also is used to refer to the edible, succulent leaves of L. sativa, which commonly are eaten raw in salads. L. sativa is the most commonly used salad vegetable (Katz and Weaver 2003).
Lettuce is used as a food plant by the larvae of some Lepidoptera.
Both the English name and the Latin name of the genus are derived from lactis, the Latin word for "milk" or milk-forming, referring to the plants milky juice. The word sativa means "common" (Katz and Weaver 2003).
Description
Lettuce belongs to the Asteraceae (or Compositae) family, which is known as the aster, daisy, or sunflower family. It is a taxon of dicotyledonous flowering plants, including chicory, globe artichoke, sunflower, yacón, safflower, and Jerusalem artichoke. The Asteraceae is the second largest family in the Division Magnoliophyta, with some 1,100 genera and over 20,000 recognized species. Only the orchid family (Orchidaceae) is larger.
Plants belonging to the Asteraceae share all the following characteristics (Judd et al., 1999). None of these traits, taken separately, can be considered synapomorphic.
- The inflorescence is an involucrate capitulum (flower head)
- Tubular/disc florets are actinomorphic, ligulate/ray florets are zygomorphic
- Anthers are syngenesious, i.e. with the stamens fused together at their edges, forming a tube
- The ovary has basal arrangement of the ovules
- One ovule per ovary
- The calyx (sepals) of the florets are modified to form a pappus, a tuft of hairs, which often appears on the mature fruit
- The fruit is an achene
- In the essential oils, sesquiterpenes are present, but iridoids are lacking.
The most common characteristic of all these plants is an inflorescence or flower head; a densely packed cluster of many small, individual flowers, usually called florets (meaning "small flowers"). The composite nature of the inflorescences of these plants led early taxonomists to call this family the Compositae.
Lettuce are those plants comprising the genus Lactuca. There are over 100 wild species of Lactuca, as well as the commercail grown Lactuca sativa.
Lettuce (Lactuca sativa) is a temperate annual or biennial plant most often grown as a leaf vegetable. The lettuce plant has a short stem initially (a rosette growth habit), but when it blooms the stem lengthens and branches, and it produces many flower heads that look like those of dandelions, but smaller. This is called bolting. When grown to eat, lettuce is harvested before it bolts.
Lettuce has been used for many centuries. The walls of ancient Egyptian tombs dating back to about 2500 B.C.E. have depictions of lettuce (Katz and Weaver 2003). The cultivated form of lettuce may have arisen from the oilseed lettuce (a thin stemmed, early bolting, wild plant with no head or rosette of leaves), via a process of selection for plants that bolted more slowly, with a thicker and shorter stem that was less bitter, and broader leaves (Katz and Weaver 2003). There are numerous mentions of lettuce in the literature, beginning with Herodotus in 550 B.C.E. (Katz and Weaver 2003).
Cultivars
There are six commonly recognised Cultivar Groups of lettuce which are ordered here by head formation and leaf structure; there are hundreds of cultivars of lettuce selected for leaf shape and colour, as well as extended field and shelf life, within each of these Cultivar Groups:
- Butterhead, also called Boston or Bibb forms loose heads; it has a buttery texture. Butterhead cultivars are most popular in Europe.
- Chinese lettuce types generally have long, sword-shaped, non-head-forming leaves, with a bitter and robust flavour unlike Western types, appropriate for use in stir-fried dishes and stews. Chinese lettuce cultivars are divided into "stem-use" types (called celtuce in English), and "leaf-use" types such as youmaicai (Chinese: 油麦菜; pinyin: yóumàicài) or shengcai (生菜).
- Crisphead, also called Iceberg, which form tight, dense heads that resemble cabbage. They are generally the mildest of the lettuces, valued more for their crunchy texture than for flavour. Cultivars of iceberg lettuce are the most familiar lettuces in the USA[citation needed]. The name Iceberg comes from the way the lettuce was transported in the US starting in the 1920s on train-wagons covered in crushed ice, making them look like icebergs.
- Looseleaf, with tender, delicate, and mildly flavoured leaves. This group comprises oak leaf and lollo rosso lettuces.
- Romaine, also called Cos, is a head-forming type with elongated leaves.
- Summer Crisp, also called Batavian, which form moderately dense heads with a crunchy texture; this type is intermediate between iceberg and looseleaf types.
Some lettuces (especially iceberg) have been specifically bred to remove the bitterness from their leaves. These lettuces have a high water content with very little nutrient value. The more bitter lettuces and the ones with pigmented leaves contain antioxidants.
Production
Uses
In some countries, it is typically eaten cold and raw, in salads, hamburgers, tacos, and many other dishes. In some places, including China, lettuce is typically eaten cooked and use of the stem is as important as use of the leaf.
Facts and figures
- Lactucarium (or "Lettuce Opium") is a mild opiate-like substance that is contained in all types of lettuce and both the Romans, and Egyptians took advantage of this property eating lettuce at the end of a meal to induce sleep.[1]
- The largest lettuce head was one that weighed 11 kg (25 lb), of the Salad Bowl cultivar, grown by Colin Bowcock of Willaston, England, in 1974.
- In the United States, 95% of all head lettuce is grown in California and Arizona.
- Yazidis consider eating lettuce taboo. See Taboo food and drink.
Diseases
Notes
- ↑ "Lettuce - Lactuca sativa - Daisy family". Hamilton, Dave (2005).
ReferencesISBN links support NWE through referral fees
- "Iceberg and Leaf Lettuce", University of California
- Bender, D. A., and A. E. Bender. 2005. A Dictionary of Food and Nutrition. New York: Oxford University Press. ISBN 0198609612.
- Herbst, S. T. 2001. The New Food Lover's Companion: Comprehensive Definitions of Nearly 6,000 Food, Drink, and Culinary Terms. Barron's Cooking Guide. Hauppauge, NY: Barron's Educational Series. ISBN 0764112589.
- Judd, W.S., C.S. Campbell, E.A. Kellogg, and P.F. Stevens. 1999. Plant Systematics: A Phylogenetic Approach. Sinauer Associates, Sunderland, MA.
- Katz, S. H., and W. W. Weaver. 2003. Encyclopedia of Food and Culture. New York: Schribner. ISBN 0684805685.
Credits
New World Encyclopedia writers and editors rewrote and completed the Wikipedia article in accordance with New World Encyclopedia standards. This article abides by terms of the Creative Commons CC-by-sa 3.0 License (CC-by-sa), which may be used and disseminated with proper attribution. Credit is due under the terms of this license that can reference both the New World Encyclopedia contributors and the selfless volunteer contributors of the Wikimedia Foundation. To cite this article click here for a list of acceptable citing formats.The history of earlier contributions by wikipedians is accessible to researchers here:
The history of this article since it was imported to New World Encyclopedia:
Note: Some restrictions may apply to use of individual images which are separately licensed.
