Usnea contexta
Family
Parmeliaceae
Flora category
Lichen – Native
Endemic taxon
No
Endemic genus
No
Endemic family
No
Structural class
Lichens - Fruticose
Current conservation status
2018 | Not Threatened | Qualifiers: SO
Brief description
Characterised by the terricolous/corticolous habit; the decumbent, straggling, rather flaccid (when moist), dichotomously divided branches, 1 mm wide at base and abruptly attenuated at apices; a smooth, glabrous, occasionally indistinctly papillate cortex; rather few secondary branches; an absence of isidia, soredia, spinules or tubercles; and fumarprotocetraric and protocetraric acids in the medulla.
Distribution
North Island: Taranaki (Mt Taranaki), Wellington (Tararua Ranges). South Island: Nelson (Mole Tops, St Arnaud Range), Canterbury (Cass, Craigieburn Range, Porter’s Pass), Otago (Mt Brewster, Matukituki Valley, Pisa Range, The Remarkables, Central Otago Mountains, Poolburn Reservoir, Maungatua), Southland (Longwood Range, Borland Saddle). Stewart Island: (Tin Range). Campbell Island: (Mt Azimuth).
Known also from South East Australia and Tasmania.
Habitat
In alpine to high-alpine grasslands and fellfield, straggling over low vegetation (Dracophyllum longifolium, D. pronum tussocks), exposed soil and rocks, often with Gowardia nigricans. Sometimes forming extensive swards and then highly visible at long distances as a pale yellow-white zone.
Detailed description
Thallus decumbent, straggling, rarely fruticose or subpendulous, 10-15 cm long, soft, flaccid when moist, yellowish-green or yellowish-white, smooth and shining, matt, repeatedly dichotomously branching, terricolous. Branches divergent, irregularly curved, 1 mm wide, abruptly attenuate at apices, irregularly jointed, primary branches ± inflated or articulate at branch points, terete, slightly faveolate-impressed in basal parts, smooth, glabrous, occasionally indistinctly papillate, secondary branches rather few, without tubercles, isidia, soredia or spinules. Apothecia not seen.
Chemistry: Thallus K+ brownish; containing fumarprotocetraric, protocetraric, and usnic acids.
Similar taxa
Stevens (1999, 2004) synonymises U. contexta with U. articulata (see Swinscow & Krog 1976), but until a more detailed study is made of the New Zealand material in relation to other populations of U. articulata, the taxa are kept separate here.
Substrate
Corticolous, terricolous
Attribution
Fact sheet prepared by Marley Ford (1 January 2022). 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.
Stevens G.N. 1999: A revision of the lichen family Usneaceae in Australia. Bibliotheca Lichenologica 72: 1–128.
Stevens G.N. 2004: Usnea. Flora of Australia 56A: 80–115.
Swinscow T.D.V. and Krog H. 1976: The Usnea articulata aggregate in East Africa. Norwegian Journal of Botany 23: 261–268.