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(Map updated: 11 August 2009)

One of the most common rock-inhabiting Porina species, P. chlorotica grows exclusively on siliceous rock often by loughs and streams and in other damp places. The thin dull brown thallus, black spherical discs (perithecia) with hard protective outer band (involucrellum), K+ grey-brown in K reaction, and three-septate spores, distinguish it from all but P. aenea which always grows on trees.

Key characteristics

• Thallus brown or blackish, perithecia small to 0.3mm diam. with involucrellum K+ grey-brown in a squash; spores three-septate
• On shaded rocks by damp places such as streams and waterbodies. When on bark, then thallus of oily appearance. N.B: P. aenea, never oily-looking.

Original text submitted by Vince J. Giavarini