Flora of New Zealand Series

Cetraria billardieri Mont., Syll. Gen. Sp. Crypt.: 322 (1856). 

For additional synonymy see Elix (loc. cit.).

Thallus ± orbicular, to 10 cm diam., often coalescing to form irregularly spreading patches, adnate to branches, twigs or dead wood. Lobes very diverse in width and separation, margins flattened, contiguous, ± placodioid, apices rotund 2-4(-7) mm wide, centrally lobes commonly contiguous forming a compact, wrinkled or puckered surface, in young thalli central parts of small, short, irregularly and sparingly branched lobes 1-2 mm wide, sometimes narrow, slightly extended, finger-like marginal lobes of similar width to young lobes are found on twig-growing plants. Upper surface pale grey to grey. Medulla solid for the most part, white. Lower surface black, wrinkled, pale brown or whitish near lobe apices. Apothecia common, subpedicellate, with a deeply wrinkled stalk and moderately wrinkled exciple, margins often involute (especially in young fruits), disc pale to dark brown, 2-10(-12) mm diam., concave at first, becoming convex and irregular with age, margins thin, symmetrical at first, becoming crenulate. Ascospores 3-5-6.5 × 5-8 µm. Chemistry: Cortex K+ yellow; medulla KC+ red, Pd-. Atranorin, chloroatranorin, physodic, 3-hydroxyphysodic, 2' -O-methylphysodic and alectoronic acids.

S: Canterbury and Otago, from east of the Main Divide to mainly coastal sites, on bark, twigs or dead wood.

Australasian