Boston lettuce and Bibb lettuce make up this variety. They form heads, but they are more loose than iceberg. ... The texture is soft and buttery, which is where this lettuce gets its name. Butterhead lettuces are more expensive than most other varieties and come with their roots still attached and submerged in water
Also called Boston and Bibb lettuce, good-quality butter lettuce will have fairly large, loose heads with thick leaves and even green coloring. Scratch the stalk and smell. A sweet or bitter smell means sweet or bitter flavor.