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Images of British Lichens

Usnea cornuta Körb.

Fruticose, tufted, much branched, variable, grey- to blueish-green, paler in well-lit situations, not blackened at the base, branches generally constricted or annulate at their junctions, finer branches sorediate and isidiate, small lateral branches rather rigid and curved, claw-like. Western and southern Britain, locally common, on trees and rocks.

Refs: Nordic Lichen Flora (2011) 4: 114, 167 (photos, printed too dark); James (2003), 17 (line illustrations); Smith et al. (2009), 923; Purvis et al. (1992), 624; Dobson (2005), 442 (photo); Dobson (2011), 449 (photo, but text entry with confusing format); van Haluwyn et al. (2009), 122-3 (photos); Valcárcel et al. (2003), 368-9 (photo); Holien & Tønsberg (2008), 66 (photo); Hinds & Hinds (2007), 493; Brodo et al. (2001), 715-6 (photo); McCune & Geiser (2009), 363 & 366 (photos).

Host to the lichenicolous fungus, Biatoropsis usnearum.

Usnea cornuta
On trunk of Common Sallow (Salix cinerea subsp. oleifolia) in damp woodland, Orielton, Pembrokeshire, May 2009.
Identity confirmed by Pat Wolseley (TLC demonstration, chemotype with salazinic and constictic acids).
Usnea cornuta in situ
Usnea cornuta, fine branches
Usnea cornuta, primary branch
Usnea cornuta, stem base
On Common Sallow (Salix cinerea subsp. oleifolia) in quaking swamp on lake edge, Orielton, Pembrokeshire, May 2009:
thallus in situ; fine branch showing soralia and isidia; branch with numerous isidiomorphs; non-blackened stem-base.
Identity confirmed by Pat Wolseley (TLC demonstration, chemotype with stictic, constictic and menegazziaic acids).

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© A.J. Silverside
Uploaded May 2009, last updated October 2013