Also known as butterheads they are all soft lettuce varieties originating from the Mediterranean basin. They have loose, round-shaped heads and loosely coiled leaves. They are tender and sweet with a mild flavour. They are grown hydroponically and sold with roots attached in plastic sleeves to preserve their freshness. The two most popular varieties - Boston and Bibb are hybrids from the original butter lettuces. Boston's leaves are wider and lighter green than Bibb's. Bibb is smaller and also has red varieties that are tastier and oh-so-pretty.