Flora of New Zealand Series

Holotype: New Zealand. Otago, Maungatua, on dead Dracophyllum, 900 m, 1933, J.S. Thomson – Herb Motyka. Isotype- CHR. Paratypes: Otago, Maungatua, bogs, 5.xii.1933, J.S. Thomson T1335 – OTA 029075; Ibid., 27.xii.1934, J.S. Thomson T1827 – OTA 029976.

Description : Flora (1985: 599)

Chemistry : Thallus K+ brownish; containing fumarprotocetraric, protocetraric, and usnic acids.

N: Taranaki (Mt Taranaki), Wellington (Tararua Ra.). S: Nelson (Mole Tops, St Arnaud Ra.), Canterbury (Cass, Craigieburn Ra., Porter's Pass), Otago (Mt Brewster, Matukituki Valley, Pisa Ra., The Remarkables, Central Otago Mountains, Poolburn Reservoir, Maungatua), Southland (Longwood Ra., Borland Saddle). St: (Tin Ra.). C: (Mt Azimuth). In alpine to high-alpine grasslands and fellfield, straggling over low vegetation (Dracophyllum longifolium, D. pronum, tussocks), exposed soil and rocks, often with Alectoria nigricans (q.v.). Sometimes forming extensive swards and then highly visible at long distances as a pale yellow-white zone. Known also from SE Australia and Tasmania (Stevens 1991, 1999, 2004b – as Usnea articulata).

Australasian

Illustrations : Martin & Child (1972: 182, pl. 54).

Usnea contexta is 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. Stevens (1999: 28, 2004b:85) synonymises U. contexta with U. articulata Ach. (see Swinscow & Krog 1976c), 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.