Black seeded Simpson lettuce

If in the south enjoy them while you can. The will bolt in no time with the heat coming on.

Leaf lettuces, spinach, collards and a lot of green leafy stuff does not do well in heat and are more beneficial when planted in the early fall.

And for your question, yes, black seeded simpson is an excellent variety. Just be sure to pick some leaves from several plants and not the whole plant when wanting lettuce and it will continue to produce. Once you see a stem come up from the middle and a flower start to form, they are done and will get bitter.

ETA: The only thing you can do now to extend their growing season is to supply a lot of shade to keep them out of direct sunlight as much as possible.

I usually plant several different varieties of leaf lettuces every fall and they will carry over until it warms up in the late spring. I never plant heading lettuces since they are a "one and done" type plant and you need to pull the entire plant to make use of it.

I still have kale, Swiss chard and collards, but the collards are getting ready to bolt, but chard and kale will continue to grow much longer.

What I love about leaf lettuce plants is they really are pretty hearty for being so delicate when small and transplant quite well with little loss.