Parmotrema reticulatum
Common name
Cracked sheet lichen
Synonyms
Parmelia reticulata, Rimelia reticulata
Family
Parmeliaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Foliose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by the corticolous/lignicolous/saxicolous habit; the ciliate lobe margins, laciniae with marginal to submarginal soredia; and the presence of atranorin, chloroatranorin, salazinic acid (major) and consalazinic acid (minor). Recent molecular studies on the P. reticulatum complex clarify the taxonomy of this group but this group still remains an aggregate in New Zealand.
Distribution
North Island: Northland (Three Kings Islands) to Wellington. South Island: Nelson to Southland. Stewart Island. Auckland Islands. Campbell Island.
Habitat
Very widely distributed on rock and wood in both coastal and inland habitats. A common and early coloniser of decorticated wood (fence posts, gates, farm railings), shade cloth, exotic trees (especially fruit trees) in parks and gardens; more commonly found in disturbed habitats than on native vegetation. A very widely distributed species worldwide, pantemperate, pansubtropical, and one of the most common foliose lichens in the world.
Detailed description
Thallus orbicular to spreading, loosely attached, to 12 cm diam., corticolous or saxicolous. Lobes rounded to sublinear, dissected, to 8 mm wide, crowded, margins sorediate, often revolute, ciliate. Upper surface dull, greenish-blue to pale greenish-grey, maculate at lobe tips (×10 lens), with patterned cracking continuing throughout thallus, sorediate. Soralia mainly marginal, causing lobe tips to become recurved and often capitate-hooded. Medulla white, often rusty-red when wet (decomposition products of salazinic acid). Lower surface dark brown to black, with a variable, shining naked marginal zone. Rhizines central, simple or squarrosely branched, black. Apothecia rare, pedicellate, to 8 mm wide, disc deeply concave when young, becoming ± plane with age, red-brown, perforate, thalline exciple sorediate, inflexed. Ascospores 13-16 × 9-11 µm. Pycnidia minute, black, punctiform, marginal.
Chemistry: Cortex K+ yellow; medulla K+ yellow→red, C−, KC+ red, Pd+ orange; containing atranorin, chloroatranorin, salazinic acid (major) and consalazinic acid (minor).
Similar taxa
Similar to P. perlatum but distinguished by the reticulate cracking of the upper surface.
Substrate
Corticolous, lignicolous, saxicolous
Attribution
Fact sheet prepared by Marley Ford (12 December 2021). Brief description, Distribution, Habitat, Features and Similar taxa sections copied from Galloway (1985) & Galloway (2007).
References and further reading
Galloway D.J. 1985: Flora of New Zealand: Lichens. Wellington: PD Hasselberg, Government Printer. 662 pp.
Galloway D.J. 2007: Flora of New Zealand: Lichens, including lichen-forming and lichenicolous fungi. 2nd edition. Lincoln, Manaaki Whenua Press. 2261 pp.
Kularatne K.I.A., & De Freitas, C. R. (2013). Epiphytic lichens as biomonitors of airborne heavy metal pollution. Environmental and Experimental Botany, 88, 24-32.
NZPCN Fact Sheet citation
Please cite as: Ford, M. (Year at time of access): Parmotrema reticulatum Fact Sheet (content continuously updated). New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/flora/species/parmotrema-reticulatum/ (Date website was queried)