Flora of New Zealand Series

Thallus foliose, lobate, distinctly dorsiventral, large, spreading, 5-25 cm diam., corticolous or saxicolous. Lobes rounded, not ciliate, 0.5-2.5 cm broad. Upper surface ashy white or tan, pseudocyphellae always present, isidia common, soredia rare. Photobiont green, ? Trebouxia. Lower surface black, rhizinate, punctate in some species. Apothecia laminal, rarely marginal, 0.5-4 cm broad, disc perforate. Ascospores ellipsoid, 11-22(-25) × 6-12 µm, 8 per ascus. Chemistry: Very diverse. Atranorin always produced in upper cortex.

Cetrelia is a predominantly Northern Hemisphere genus in the family Parmeliaceae, with a centre of speciation in East and South East Asia [Culberson and Culberson Contr. U.S. natn. Herb. 34 (7): 449-558 (1968)]. It is rarely represented in Southern Hemisphere floras. One species is present in New Zealand.