Flora of New Zealand Series

Lichen parietinus L., Sp. Pl.: 1143 (1753).

Thallus rosette-forming to irregularly spreading, to 10 cm diam., loosely attached, corticolous. Lobes 3-6 mm long and 2-5 mm wide, thin, smooth to irregularly wrinkled or weakly plicate or pitted, often distinctly faveolate, with raised, entire, often sinuous margins. Upper surface yellow-orange or greenish-yellow to pale greenish-grey in shaded situations, matt or shining, smooth to ± faveolate-plicate. Lower surface pale yellowish or whitish, rhizinate. Rhizines sparse, short, simple, white. Apothecia sessile, ± central, lecanorine, to 5 mm diam., margins thin, persistent, concolorous with thallus, often inflexed, disc plane or subconcave, yellow-orange, matt. Ascospores ellipsoid, 11-26 × 6-9 µm.

N: S: St: A: C: Throughout, very widely distributed, coastal and lowland, uncommon inland, s.l. to 1500 m.

Cosmopolitan

X. parietina is a very wide-ranging species in New Zealand and one especially characteristic of eutrophic habitats. Although most commonly collected from bark it will also colonise bone, glass, slate and tile. It is more frequently epiphytic on introduced trees and shrubs (especially fruit trees) than on native vegetation, though it is frequent on mangrove (Avicennia resinifera) in northern New Zealand, and common on Hoheria angustifolia in eastern South I., localities. Murray ( loc. cit. ) considers that X. parietina may be introduced into New Zealand. It is an extremely variable species, especially in terms of thallus colour, and all of the infraspecific taxa accepted by Murray are merely environmentally induced modifications and of no taxonomic validity. It is distinguished from X. ligulata by the thinner, broader, plane or subconvex lobes which are without adventitious marginal lobules, by the ± raised margins and by the wrinkled-pitted or faveolate upper surface.