From The Buffalo Seed Company:
 
LETTUCE (Lactuca sativa) (leaves 45-50 days) — This is a delicious butterhead lettuce landrace originating in France. Butterhead varieties have a buttery texture. In particular, this variety has a mild and sweet flavor, forms nice loose heads, and is a great producer. Great for gourmet cooks looking to bring things to the next level. Serious salad material. A landrace is a traditional variety with deep cultural roots that is often dynamic, diverse, and adapted to specific environmental conditions.