Lettuce - Lettuce (English spelling)

Japanese: レタス - れたす（英語表記）lettuce

It is a biennial plant of the Asteraceae family. Its Japanese name is lettuce. It has been used as a leafy vegetable in Europe since ancient times, and has evolved into various lineages and cultivars. The leaves are elliptical or oblong, and the stems do not grow much until the middle of the growth period. Some leaves overlap and form heads, while others do not. When the stems and leaves are damaged, a white milky liquid comes out. In summer, the plant bolts and grows to a height of over 1 meter, branches at the top, and produces yellow chrysanthemum-like flower heads 2 to 3 centimeters in diameter. It blooms early in the morning and closes before noon. The seeds are achene, oblong, flat, 3 to 4.5 mm long, and come in white, yellow, and black colors. The seeds are photophilic and have the characteristic of being difficult to germinate in the dark.

Commonly cultivated species include the heading and semi-heading Lactuca sativa L. var. capitata L. and the non-heading Lactuca lettuce var. asparagina Bailey.

Eggplant is also called head lettuce or cabbage lettuce. When it has 10 or more leaves, it forms a head, which is 10 to 20 centimeters in diameter. The origin of head lettuce is unclear, but it became popular in Europe in the 16th century. It was introduced to Japan during the Meiji period. There are many varieties with leaves that are bright green or brownish purple. Among these, butterhead lettuce does not form a dense head, but is loosely semi-headed, and the leaves are extremely soft and melt in the mouth. In Japan, it is commonly called salad lettuce.

Lettuce has long, overlapping leaves, and as the leaves increase, the stem grows longer. The stem is thick and soft, measuring 3cm in diameter. The leaves are scraped off and eaten, and the stem, which has grown to 30-50cm, is eaten like asparagus, hence the name asparagus lettuce. It is also called kuki lettuce. Lettuce, the leaves of which are scraped and eaten, was already in use in Persia in the 6th century BC, and later spread to Greece and Rome, before spreading throughout Europe. It had reached China by the 5th century, and had been introduced to Japan by the 10th century. This is the native lettuce.

Other commonly used lettuce include cos lettuce and curled lettuce (Japanese name: Chirimenjisha) var. crispa L. Cos lettuce has oblong leaves, 20-30cm long, almost upright, and grows in a semi-head shape similar to Chinese cabbage, with the inner leaves being blanched. It has been cultivated in Italy, which has a warm climate, since the Middle Ages, and is common in England and France, but is rarely grown in Japan. Curled lettuce has few leaves and is curly. It comes in head and semi-head varieties, and is available in green as well as reddish purple colors.

In Japan, the area of production for summer/autumn lettuce is 8,880 hectares, with an annual production of 248,500 tons (2005), mainly in Nagano (68%) and Gunma (12%). The area of production for winter lettuce is 8,170 hectares, with an annual production of 185,000 tons (2005), mainly in Ibaraki (17%), Kagawa (14%), and Hyogo (13%), followed by Shizuoka and Nagasaki prefectures. The area of production for spring lettuce is 4,440 hectares, with an annual production of 118,100 tons (2005), mainly in Ibaraki (31%), Nagano (14%), and Hyogo (10%), followed by Kagawa prefecture. It is produced and supplied year-round in urban suburbs, highland areas in the summer, and warm areas in the winter. Seeding takes place from March to October, usually in a nursery bed, and the young seedlings are planted in the main field. Autumn sowing produces the best head formation. During the winter, they are grown in greenhouses and tunnels.

[Hoshikawa Kiyochika]

use

Lettuce is considered a representative vegetable that is eaten raw, and is rich in vitamin A. It is essential for salads, and salad lettuce in particular has the most suitable qualities. Curl lettuce is popular for its crisp, crunchy leaves. It is also used in soups and sandwiches. Asparagus lettuce and cos lettuce leaves have the slight bitterness of lettuce and are not suitable for eating raw, so they are boiled once before cooking. Desserts are also used in salads and dressed with sesame paste. Dessert stems are mainly used in Chinese cuisine, where they are boiled and seasoned in various ways.

[Hoshikawa Kiyochika]

"Lettuce - Cultivation Types and Cultivation Methods" edited by Yuji Kondo (1980, Rural Culture Association)" ▽ "Lettuce Physiology and Cultivation Techniques - New Vegetable Cultivation Techniques 1" edited by the Agriculture and Horticulture Editorial Department (1986, Seibundo Shinkosha)

Head lettuce (crisp type)
©Shogakukan ">

Head lettuce (crisp type)

Head lettuce (lettuce)
©Shogakukan ">

Head lettuce (lettuce)

Cos lettuce
Also known as romaine lettuce ©Shogakukan ">

Cos lettuce

Curl lettuce (pleated lettuce)
©Shogakukan ">

Curl lettuce (pleated lettuce)

Pinkrossa
A hybrid of chili pepper and endive ©Shogakukan ">

Pinkrossa

Lettuce cultivation
It has been used as a leafy vegetable in Europe for a long time, and was introduced to Japan during the Meiji period. It is produced and supplied year-round in highlands where it is cool in summer and warm in winter. It is considered a representative vegetable for eating raw .

Lettuce cultivation

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

キク科の一、二年草。和名をチシャ（萵苣）という。ヨーロッパで古くから葉菜として利用され、いろいろな系統、品種群に分化している。葉は楕円(だえん)形ないし長形で、生育中期までは茎はほとんど伸びず、葉は重なり合い結球するものと、結球しないものとがある。茎葉は傷つけると白い乳液が出る。夏にとう立ちして高さ1メートル余になり、上部は枝分れし、黄色の径2～3センチメートルのキク状の頭花をつける。早朝開花し昼前には閉じる。種子は痩果(そうか)で長楕円形で扁平(へんぺい)、長さ3～4.5ミリメートル、白のほかに黄、黒色のものがある。種子は好光性で暗黒下では発芽しにくい特性がある。

　よく栽培される系統には、結球・半結球性のタマヂシャ（玉萵苣）Lactuca sativa L. var. capitata L.と、非結球性のカキヂシャ（掻萵苣、別名アスパラガスレタスasparagus lettuce）var. asparagina Baileyがある。

　タマヂシャはヘッドレタスhead lettuceまたはキャベツレタスcabbage lettuceともよばれる。葉は10枚以上になると結球し、球は径10～20センチメートルになる。結球性レタスの起源年代は明らかでないが、ヨーロッパで16世紀から普及した。日本へは明治時代に導入された。葉は鮮緑色のほか褐紫色のものなど品種が多い。このなかで葉が密に結球しないで、緩く半結球性となり、葉質がきわめて柔らかく、口中で溶けるようなという意味でバターヘッドとよばれる。日本ではこれを一般にサラダナとよんでいる。

　カキヂシャは葉は長形で多数重なり、葉が増えるにつれてすこしずつ茎が伸びる。茎は太く径3センチメートルで柔らかい。葉を順次掻(か)き取って食べ、また伸びて30～50センチメートルになった茎をアスパラガスのように食べるのでアスパラガスレタスの名がある。他にクキチシャ（茎萵苣）ともいう。葉を掻いて食べるレタスはすでに紀元前6世紀にペルシアで利用され、以降、ギリシア、ローマに普及しヨーロッパに広まった。5世紀までには中国に伝わり、日本へは10世紀までには入っていた。これが在来のチシャである。

　このほかに、よく利用されるものに、コスレタスcos lettusと、カールレタスcurled lettuce（和名チリメンヂシャ）var. crispa L.がある。コスレタスは葉は長楕円形、長さ20～30センチメートル、ほぼ直立性で、ハクサイに似た半結球状になり、内部の葉は軟白されている。温暖な気候のイタリアで中世から栽培され、イギリス、フランスに多いが、日本ではほとんど栽培されていない。カールレタスは葉数は少なく、葉は縮れている。結球性と半結球性のもの、色も緑のほかに紅紫色などがある。

　日本での生産は、夏秋レタスが8880ヘクタール、年産24万8500トン（2005）、主産地は長野（68％）、群馬（12％）。冬レタスが8170ヘクタール、年産18万5000トン（2005）、主産地は茨城（17％）、香川（14％）、兵庫（13％）ついで静岡、長崎県など。春レタスが4440ヘクタール、年産11万8100トン（2005）、主産地は茨城（31％）、長野（14％）、兵庫（10％）ついで香川県などとなっており、都市近郊地、夏は高冷地、冬は温暖地などで周年生産供給されている。播種(はしゅ)は3～10月、普通は苗床に播種し、子苗を本畑に定植する。秋播(ま)きがもっとも結球性がよい。冬季はビニルハウス、トンネル内で栽培する。

［星川清親］

利用

レタスは生食野菜の代表とされ、ビタミンAを多く含む。サラダには不可欠で、とくにサラダナはもっとも適した品質を備えている。カールレタスは葉質が縮みをもつとともに歯切れがよいのが好まれる。またスープなどに入れたり、サンドイッチに挟んだりする。アスパラガスレタスおよびコスレタスの葉はレタス本来の淡い苦味をもち、生食には向かないので、一度ゆでて料理する。カキヂシャも和(あ)え物、ごまよごしなどにする。カキヂシャの茎はおもに中華料理に用いられ、ゆでてから種々に味つけする。

［星川清親］

『近藤雄次編著『レタス――作型とつくり方』（1980・農山漁村文化協会）』▽『農耕と園芸編集部編『レタス生理と栽培技術――野菜栽培の新技術1』（1986・誠文堂新光社）』