Question: Which raw vegetables are popularly eaten in salads?
About the article "Salad", section "Vegetable salad".

Candidate passages:
Thai salads often do not have raw vegetables or fruit as their main ingredient but they use (minced) meat, seafood, or noodles instead.
Similar to salads in the West, these dishes have in common that they (often) use a souring agent (in Thailand usually lime juice) and feature the addition of fresh herbs and other greens in their preparation.
Thai salads are not served as entrées but normally eaten as one of the main dishes in a Thai buffet-style meal, together with rice (depending on the region this can be glutinous rice or non-glutinous rice) or the Thai rice noodle called "khanom chin".
Specialised "khao tom kui" (plain rice congee) restaurants also serve a wide variety of Thai salads of the "yam" type as side dishes.
Many Thai salads, for instance the famous "som tam", are also eaten as a meal or snack on their own. 
If leaves are cooked for food, they may be referred to as boiled greens.
Leaf vegetables may be stir-fried, stewed, steamed or consumed as salad (without cooking).
Leaf vegetables stewed with pork are a traditional dish in soul food, and southern U.S. cuisine.
They are also commonly eaten in a variety of South Asian dishes such as saag.
Leafy greens can be used to wrap other ingredients like a tortilla.
Many green leafy vegetables, such as lettuce or spinach, can also be eaten raw, for example in sandwiches or salads.
A green smoothie enables large quantities of raw leafy greens to be consumed by blending the leaves with fruit and water. 
Vietnamese eggplants are used in Vietnamese cuisine in stir fries, soups and salads.
They are also eaten raw or pickled. 
As described around 50 AD, lettuce leaves were often cooked and served by the Romans with an oil-and-vinegar dressing; however, smaller leaves were sometimes eaten raw.
During the 81–96 AD reign of Domitian, the tradition of serving a lettuce salad before a meal began.
Post-Roman Europe continued the tradition of poaching lettuce, mainly with large romaine types, as well as the method of pouring a hot oil and vinegar mixture over the leaves.
Today, the majority of lettuce is grown for its leaves, although one type is grown for its stem and one for its seeds, which are made into an oil.
Most lettuce is used in salads, either alone or with other greens, vegetables, meats and cheeses.
Romaine lettuce is often used for Caesar salads, with a dressing that includes anchovies and eggs.
Lettuce leaves can also be found in soups, sandwiches and wraps, while the stems are eaten both raw and cooked.
The consumption of lettuce in China developed differently than in Western countries, due to health risks and cultural aversion to eating raw leaves.
In that country, "salads" were created from cooked vegetables and served hot or cold.
Lettuce was also used in a larger variety of dishes than in Western countries, contributing to a range of dishes including bean curd and meat dishes, soups and stir-frys plain or with other vegetables.
Stem lettuce, widely consumed in China, is eaten either raw or cooked, the latter primarily in soups and stir-frys. 
These basils are eaten raw, or served alongside pho and other Vietnamese noodle soups, in salads or in stir fried dishes.