A cool-weather leafy cabbage relative grown for its broad, leathery, blue-green leaves that grow in a loose upright rosette on a thick stem — never forming a head ("acephala" is Greek for headless). A biennial almost always grown as an annual, it sweetens after a fall frost and, in mild-winter regions, keeps producing leaves through winter until it bolts in spring. One of the most cold-tolerant vegetables in the cabbage family.