Pincushion Sunburst Lichen - Xanthoria polycarpa 

Xanthoria polycarpa is a lichenized fungi with foliose thallus (the vegetative body) forming small cushions up to 3 cm wide or larger colonies, with short and narrow, convex lobes, frequently almost completely covered with apothecia (the fruiting bodies, cup-like in this species).

Xanthoria polycarpa is widespread on nutrient-enriched trees, especially on small twigs where it forms clusters of apothecia in axils of branches; becoming common as an indicator of nitrogen deposition.

This species has circumpolar distribution extending into temperate regions. It is very widespread and, because of its bright yellow-orange color, easy to identify.

[Fungi - Ascomycota - Lecanoromycetes - Teloschistales - Teloschistaceae - XanthoriaXanthoria polycarpa (Hoffm.) Th. Fr. ex Rieber]

References: [1] - [2] - [3]

Photo credit: ©Richard Droker (CC BY-NC-ND 2.0) | Locality: not indicated (2009)

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Maritime Sunburst Lichen

Xanthoria parietina on a live branch of Common hazel (Corylus avellana).

Xanthoria parietina (Teloschistaceae) is a conspicuous yellow foliose lichen that contain a compound that acts as both a sunscreen for the algal partner and also protects them from harmful UV rays. Hence this species is often found in sunny exposed places.

This lichen is tolerant of high levels of nitrogen, especially ammonia, and is common on trees and buildings near farmland. So, Xanthoria parietina can be used as a monitor for nitrogen in the atmosphere.

The species is widespread over Britain, Europe and America but in tropical countries and in Australia it is rather rare. 

Reference: [1]

Photo credit: ©Erminio Ferrari

Locality: unknown

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