Thallus small-foliose, squamulose or lobate, closely attached, sometimes appearing crustose. Lobes very narrow, strap-shaped to somewhat rounded or linear, contiguous to crowded, margins entire to dissected, plane or sorediate, the soredia often covering large areas of the thallus, with lobes visible only at margins. Upper surface yellow, not turning purple on addition of KOH. Medulla white. Photobiont green, . Apothecia small, to 1.5 mm diam., sessile, concave, disc yellow-green. Ascospores many (16-32) per ascus, colourless, simple or 1-septate. is a cosmopolitan genus of c. 7 species included in the family Candelariaceae, a characteristic of which is the production of pulvinic acid derivatives giving the strong yellow colour to the thallus. is distinguished from by the foliose-lobate nature of the thallus, a feature most easily recognised at the thallus margins. One species is present in New Zealand.