Flora of New Zealand Series

Parmelia soredians Nyl., Flora 55: 426 (1872).

Thallus orbicular to spreading, closely attached, 5-12 cm diam., corticolous or lignicolous. Lobes small (to 5 mm wide) confluent, subirregular, rounded, margins shallowly incised. Upper surface plane, shining, wrinkled centrally, yellowish-green (usnic acid in cortex), sorediate. Soralia large, rounded, pustular, densely crowded centrally, soredia very fine, dense, farinose, yellow. Lower surface black, shining, with a shining black or brown naked marginal zone. Rhizines simple, numerous, black or pale. Apothecia (not seen in New Zealand material) rare, sessile, 1-4 mm diam., thalline exciple pustular. Chemistry: Cortex K+ yellow; medulla K+ yellow → red, C-, KC+ red, Pd+ orange. Salazinic acid and atranorin.

N: Wellington (near Bunnythorpe). S: Marlborough (Stephens I.). Mainly on decorticated wood (fenceposts, gates) rarely on bark or rocks.

Cosmopolitan

Similiar to P. pseudosorediosa but distinguished by the discrete, orbicular soralia and salazinic acid in the medulla.