Lettuce

Lettuce is a temperate annual plant most often grown as a leaf vegetable. In Western countries, it is typically eaten cold and raw, in salads, hamburgers, tacos, and several 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.

A 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.

Varieties

Commonly recognized types of lettuce include:

• Iceberg lettuces form tight, dense heads that resemble cabbage. They are generally the mildest of the lettuces, valued more for their crunchy texture than for flavor. Varieties of iceberg lettuce are the most familiar lettuces in the USA.
• Crisphead lettuces form moderately dense heads with a crunchy texture; this type is intermediate between iceberg and looseleaf types.
• Looseleaf
• Romaine, also called cos is a head-forming type with elongated leaves.
• Butterhead, also called Boston or bibb forms loose heads; it has a buttery texture.
• Batavia is similar to butterhead.
• Chinese lettuce types generally have long, sword-shaped, non-head-forming leaves, with a more bitter and robust flavor than Western types, appropriate for use in stir-fried dishes and stews. Chinese lettuce varieties are divided into "stem-use" types (called celtuce in English), and "leaf-use" types such as youmaicai (Chinese: 油麦菜; pinyin: yóumàicài).

There are hundreds of varieties of lettuce within these categories.

Some lettuces (especially iceberg) have been specifically bred to remove the bitterness from their leaves. These lettuces are have a high water content with very little nutrient value. The more bitter lettuces and the ones with pigmented leaves contain antioxidants.

Trivia

The largest lettuce head was one that weighed 25 lb (11 kg), of the Salad Bowl variety, grown by Colin Bowcock of Willaston England in 1974.