Eruca sativa, Diplotaxis spp. 20 days to baby greens, 40 days to full size.
This is your standard salad arugula, with long, dark, lobed leaves suitable for salad mix or bunching. Arugula will brighten up your shoulder season salads, and is a good overwintering greenhouse crop as well. Let it go to seed and it will re-plant itself in a dense, low-maintenance stand. Cut at the baby-leaf stage or during cool weather, arugula is quite mild. During hot weather or at mature stage it can get quite spicy.
The white flowers are also edible, with a spicy, nutty flavor that makes an excellent salad topping.