Technically not a type of lettuce so much as a mix of baby lettuce leaves, mesclun is usually packaged and sold as “spring mix” (even though, yeah, you can buy it year-round). TBH, I think of ...

Leafy greens may not last as long as head lettuces, but you can extend their life as long as possible with a little extra legwork. Lettuces like a mesclun mix or arugula often come in clamshell ...