Ancient sources suggest that the ancient Egyptians already knew lettuce species as a vegetable. The plants can be seen in pictures from around 2700 BC. At least three forms of lettuce have survived from ancient Greece, and Lactuca sativa was also used by the Romans. With them it migrated to Central Europe. In the Middle Ages it was found as a medicinal and useful plant in many monastery gardens north of the Alps, where the first head-forming varieties were bred.
It is unclear from which original plant our lettuce varieties originate; several Lactuca, i.e. lettuce species, are possible. Presumably, the wild herb compass lettuce, Lactuca serriola, which is widespread in our region, is one of their ancestors. The genus name Lactuca contains the Latin word "lac" for "milk", which refers to the milky sap of the plant.
Lactuca sativa is an annual plant with rosette-like leaves. They grow densely packed at the beginning - this is appreciated during harvesting. Only when it starts to flower the shoot stretches; the lettuce "shoots". It develops a yellow inflorescence. The plant belongs to the composite plants.
Today, several varieties of this type of lettuce are distinguished. In addition to the common head lettuce, this includes the romaine or romana lettuce, Lactuca sativa var. longifolia, also known in Switzerland by its original name "Lattich". As the Latin term suggests, it has elongated leaves. They are thicker and firmer than lettuce and taste stronger, even a little nutty depending on the variety. They evoke that fresh crunchy feeling when you eat it.
Sometimes lettuce is also called summer endive because of its similarity to endive lettuce. In the past, its leaves were tied together so that the inside remained bright green and tender, as the name "tied lettuce” suggests. In modern cultivars, the leaves are dense by themselves. A lettuce plant grows up to 40 centimetres long and weighs 300 grams.
Romaine lettuce is rich in minerals: It is particularly rich in potassium and iron, as well as phosphorus, calcium, sodium, zinc and magnesium. With 24 milligrams per hundred grams, it contains almost twice as much vitamin C as lettuce, plus various B vitamins, vitamin E, beta-carotene and folic acid - both especially in the red-leaved varieties. Its taste is characterised by apple and citric acid, as well as fructose and dextrose. And finally, it provides the leaf pigment chlorophyll in large quantities.
Originally, lettuce comes from the Mediterranean region. Thanks to cold frames and greenhouses, however, it also thrives in our latitudes. Today it is available worldwide and all year round. Between March and May, it can also be sown outdoors in our country, so that it can be found in many gardens.
The fact that we prefer salad in summer is not only because it is a light food and consists of 95 percent water - it also has cooling properties. In naturopathy, this helps to reduce fever. In the past, the crushed leaves were placed on the head of fever patients. Processed into pulp, it was used as a wound dressing, for example for burns and inflammations.
The milky sap contains bitter substances that are similar to opiates. In this way, they have an analgesic, calming effect, dampen excitement, make you tired and promote healthy sleep. In the Middle Ages, the dried milky sap was used as a calming, sleep-inducing medicine. In monasteries, its excitement-dampening effect was also valued to preserve chastity. Sensitive people are said to be able to feel the calming effect just by eating a salad. In the past, it was assumed that the milky sap can stimulate the milk flow of breastfeeding mothers. In fact, researchers have now found a substance with this effect. In addition, these active ingredients help with spasmodic coughs and asthma.
The bitter substances are also responsible for the digestive effect of romaine lettuce, as they stimulate the release of digestive juices and promote blood circulation in the abdominal organs. Lactuca sativa is also rich in dietary fibre, which stimulates intestinal function. This prevents constipation. Thanks to chlorophyll and iron, it stimulates blood formation. It also strengthens the immune system and detoxifies the liver.
We most often eat lettuce raw as a fresh salad. It is the main ingredient of the dish "Caesar Salad", which is very popular in the USA. The oil in the dressing ensures that the body can absorb the fat-soluble ingredients such as beta-carotene and the bitter substances. But romaine lettuce can also be prepared as a vegetable: The lettuce hearts can be roasted or stewed in whole. As a cooking salad, the leaves are processed like savoy cabbage.