Species: Caloplaca ferruginea
Photos: On hazel and willow. The Burren and Gougane Barra, Ireland Photo immediately below: BLS Burren meeting 2009
Entire or immersed thin, smooth, pale whitish-grey thallus. Large bright-orange apothecia, often with uneven, flexose margins. Asci are 8-spored, spores ellipsoid, polarilocular, 12-14 x 6-8 Ám, septum 5 Ám to approx 1/2 length of ascospore. Micro photos below.
K+ crimson / purple.
Mainly found on Hazel and Willow, also on twigs and trunks of other basic-barked trees. Increasing in Ireland, rare in UK
Similar: C. crenularia. Found on siliceous rocks.