Lettuce, Buttercrunch

Buttercrunch lettuce is a type of butterhead lettuce with soft, dark green leaves that form a loose head around a pale center: 
Buttercrunch lettuce has a rich, buttery flavor. 
The leaves are crispy and juicy, while the center leaves are blanched and have a buttery texture. 
Buttercrunch lettuce is heat tolerant and slow to bolt, so it stays mild longer than other lettuces. 
Buttercrunch lettuce is a good choice for growing in cool seasons, but can be grown all winter if protected. It prefers full sun to partial shade, and the ideal temperature is 60–80°F.