The leaves are arranged in rosettes. The blades are usually large, from narrowly lanceolate to oval, with the base ranging from heart shaped to very gradually narrowing, and can have a sharply pointed or blunt tip. The leaf margin is always entire, but in some species and forms can be rather wavy. Basal leaves are carried on stalks that can be short or longer than the leaf blade in various species. Stem leaves are smaller and often narrower, and are unstalked or clasping the stem. All leaves are covered with hairs that are usually bristly, or occasionally soft. The leaves are often prominently spotted in black and blue, or sometimes in pale green, or unspotted. The spots are due to the presence of foliage air pockets. These pockets, which cool the lower leaf surface, mask the presence of chlorophyll.