Modifiers matching lettuce:

• small,
• bitter,
• crisp,
• hearty,
• dark,
• mixed,
• leafy,
• torn,
• fresh,
• clean,
• new,
• mild,

Simple categories matching leafy:

• evergreen,
• essence,
• green,
• vegetable,
• soil,
• veggie,
• herb,
• material,
• shrub,
• spice,
• vegetation,
• plant,
• substance,
• forage,
• crucifer,
• object,
• veg,
• lettuce,
• perennial,
• item,
• tree,