Irish lichens

Collema nigrescens

Order: Peltigerales       Family: Collemataceae

Species: Collema nigrescens

Growth type foliose.
Photos: Killarney National Park, Co. Kerry, SW Ireland.
Identified by John Douglass

Dark olive-green to brown-black lobes, strongly ridged, sometimes with coarsely granular isidia. Apothecia are usually very abundant, the margins sometimes isidiate.

Rare in Ireland, few recent records. Occurs on nutrient-rich bark of mature deciduous trees. In the UK occasionally recorded from seepage tracks on coastal rocks. Chemical reactions negative.

Similar: Collema subnigrescens, often fertile, isidia absent.
Collema furfuraceum, isidiate but discs rare.

Collema nigrescens

Collema nigrescens
Collema nigrescens November 2009

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