Lettuce (Lactuca sativa) is an annual leaf vegetable of the daisy family, Asteraceae.
It is without doubt the world’s most popular salad plant.
Lettuce was first cultivated by the ancient Egyptians who turned it from a weed whose seeds were used to produce oil, into a food plant grown for its succulent leaves and oil-rich seeds.
According to Herodotus, lettuce was served on the tables of the Persian kings of the 6th century BC.
Lettuce spread to the Greeks and Romans, the latter of whom gave it the name lactuca, from which the English lettuce is ultimately derived.
Lettuce traveled with the Romans into Western Europe and east all the way to China, establishing itself at multiple points along its journey.
Columbus evidently carried lettuce to the New World, for its culture was reported on Isabela Island (now called Crooked Island) in the Bahamas in 1494. Lettuce was doubtless among the first garden seeds sown in every European colony on this continent.
Between the late 16th century and the early 18th century, many varieties were developed in Europe, particularly Holland.
Plants generally have a height and spread of 15 to 30 cm (6 to 12 in). The leaves are colorful, mainly in the green and red color spectrums, with some variegated varieties.
Four most widely grown varieties of lettuce are:
1) Celtuce, or asparagus lettuce (variety augustana), with narrow leaves and a thick, succulent, edible stem
2) Head or cabbage lettuce (variety capitata), with the leaves folded into a compact head
3) Leaf or curled lettuce (variety crispa), with a rosette of leaves that are curled, finely cut, smooth-edged, or oak-leaved in shape
4) Cos or romaine lettuce (variety longifolia), with smooth leaves that form a tall, oblong, loose head
There are two classes of head lettuce:
1) The butterhead types, such as Bibb lettuce, with soft heads of thick oily-textured leaves
2) Crisphead types, such as iceberg lettuce, with brittle-textured leaves that form very hard heads under proper temperature conditions
In some countries, lettuce 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 the use of the leaf.
There are only 15 calories in 100 grams (3.5 ounces) of lettuce.
Lettuce is an excellent source of vitamin A (in the form of carotenoids), vitamin K, folate and molybdenum. It is also a very good source of dietary fiber, manganese, potassium, biotin, vitamin B1, copper, iron and vitamin C. It is also a good source of vitamin B2, omega-3 fatty acids, vitamin B6, phosphorus, chromium, magnesium, calcium and pantothenic acid.
The health benefits of lettuce include lower cholesterol levels, boosts heart health, promotes brain health, regular sleep, anxiety control, boosts immunity, skin care benefits, promotes vision health, lower inflammation, fights anemia, support weight loss and prevention of cancer.
Today, China is the largest producer of lettuce in the world.
Lettuce is produce year round in the United States. Although lettuce is produced in many states, California and Arizona dominate US production.
Romaine lettuce is often used for Caesar salads, with a dressing that includes anchovies and eggs.