From a Worcester Allotment: About Lettuce

Friday, 9 July 2010

Lettuce (Lactuca sativa) is a temperate annual or biennial plant of the daisy family Asteraceae.
It is most often grown as a leaf vegetable.
In many countries, it is typically eaten cold, raw, in salads, sandwiches, hamburgers, tacos, and in 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.
Both the English name and the Latin name of the genus are ultimately derived from lac, the Latin word for “milk”, referring to the plant’s milky juice.
Mild in flavour, it has been described over the centuries as a cooling counterbalance to other ingredients in a salad.
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:

Chinese lettuce (L. sativa var. asparagina) types generally have long, sword-shaped, non-head-forming leaves, with a bitter and robust flavour unlike Western types, 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: 油麥菜; pinyin: yóumàicài) or shengcai (生菜/唐生菜), respectively.

Crisphead, also called Iceberg, forms tight, dense heads that resemble cabbage.

They are generally the mildest of the lettuces, valued more for their crunchy texture than for flavour.
The name Iceberg refers to the crisp, cold, clean characteristics of the leaves.

Looseleaf (L. sativa var. crispa) has tender, delicate, and mildly flavoured leaves.

This group includes oak leaf and lollo rosso lettuces.
Loose leaf lettuce is a lettuce variety which does not form a compact head.
There are numerous different types of loose leaf lettuce, with basic red and green being the most common.
This lettuce varietal is very easy to grow and it can be flexibly used in a wide variety of recipes, making it a popular choice for the garden and market.
Most markets and greengrocers carry several types of loose leaf lettuce, and it is also possible to grow at home.

Romaine (L. sativa var. romana), also called Cos, grows in a long head of sturdy leaves with a firm rib down the centre.

Unlike most lettuces, it is tolerant of heat.
The thick ribs, especially on the older outer leaves, should have a milky fluid which gives the romaine the typically fine-bitter herb taste.
Romaine is the usual lettuce used in Caesar salad.
Romaine is the usual lettuce in Middle Eastern cuisine.
Romaine is usually eaten as salad in North America.
Most dictionaries trace the word cos to the name of the Greek island of Cos, from which the lettuce was presumably introduced.

Summer Crisp, also called Batavian, forms moderately dense heads with a crunchy texture.

This type is intermediate between iceberg and looseleaf types.
The outer leaves are thick, crisp and flavoursome, the often conic heart/head is crisp and sweet.
In some varieties, the outer leaves can be harvested as a loose leaf until the head starts to form.
These are quite large lettuces, and need good fertility.
Their particular virtue, apart from their top rate taste, is their ability to 'stand' without bolting.

Some lettuces (especially iceberg) have been specifically bred to remove the bitterness from their leaves. These lettuces have high water content and so less "nutritionally dense" than are the more bitter lettuces and those with darker leaves.
While all lettuces contain antioxidants and Vitamin K, romaine and looseleaf lettuce contain five to six times the Vitamin C and five to ten times the Vitamin A of iceberg.
Romaine and butterhead lettuce are good sources of folate.

Friday, 9 July 2010