Usnea cornuta
Synonyms
Usnea arida Motyka,
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 corticolous habit; the compact, shrubby nature of the thallus; a wide medulla (U. fragilescens-group); narrow axis, branches slightly to markedly inflated; numerous, punctate soralia that may become in part isidiose and confluent; and salazinic and norstictic acids in the medulla (K+ yellow→red).
Distribution
North Island: Northland to Wellington. South Island: Nelson to Southland. Stewart Island: Widely distributed, lowland and coastal.
Known also from Great Britain, Europe, Macaronesia, North America, Mexico, India, Japan, Taiwan, Indonesia, Australia and Chile.
Habitat
Epiphytic on bark of Metrosideros, Leptospermum, Olearia, Pterophylla, fruit trees, dead twigs, stumps, fenceposts, wooden gates and out buildings.
Detailed description
Thallus fruticose to subpendulous, spreading from base, 5-10 cm tall, green to yellowish-green, often brownish-red in parts, soft and flaccid when wet, irregularly subdichotomously branching, corticolous. Branches 0.5-2.5 mm thick, inflated, secondary branches numerous, often articulate-cracked at branch points, cortex glossy especially towards base, papillate, rarely with small, white, scattered, punctate pseudocyphellae, possibly formed through abrasion of papillae, sorediate, with many lateral fibrils, seudoisidia and spinules, giving the plant a bristling appearance. Soredia discrete or crowded, often becoming pseudoisidiate. Apothecia not seen.
Chemistry: Thallus and medulla K+ yellow→red, C−, KC+ red, Pd+ orange; containing salazinic, norstictic, and usnic acids.
Similar taxa
Can be confused with U. dasaea, U. inermis and U. rubicunda. Chemically it can be distinguished from U. inermis because U. inermis is never K+. Usnea cornuta and U. dasaea are both K+ but U. dasaea will slowly turn a deep dark red because of the galbinic acid. Also the axis is very narrow in U. cornuta, with a lax medulla.
Substrate
Corticolous
Etymology
cornuta: Knobbed
Attribution
Fact sheet prepared by Marley Ford (1 May 2022). Brief description, Distribution, Habitat, and Features 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.