Irish lichens

Collema cristatum

Order: Peltigerales       Family: Collemataceae

Species: Lathagrium cristatum (Collema cristatum)

Growth type foliose.
Photos: On limestone in the Burren, Co. Clare and on wall, Foynes, Co. Limerick, Ireland.

Round, semi-circular or irregular thallus, centre often disintergrating with age. Lobes thinnish, radiating, convoluted, margins wavy, entire or incised. Upper surface dark olive-green to black, lower with white tufts of hapters. Sessile or stalked apothecia with even margins, usually crowded, +/- marginal, but sometimes absent.

Common throughout Ireland on hard calcareous rocks, mortar and tombstones. Chemical reactions negative.

Collema cristatum

Collema cristatum

Collema cristatum. July 2009

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