Cladonia stereoclada Abbaye
Species very similar to certain forms of Cladonia furcata s.l. or Cladonia rangiformis s.l., but which differs by its thinner podetia of 0.3-0.6 mm in diameter, more or less erect and flexuous, forked, a cross section shows a non-hollow, "pencil" structure formed of a thick, dense, whitish outer layer and a more or less gelatinous, grayish central axis (sometimes, but rarely, the central axis is hollow but then very narrow). External surface smooth, grayish, greenish-gray, brownish-gray, more or less corticate and marbled in appearance in humid weather. C-, K-, CK-, P+ red, UV-. Macaronesian and oceanic species but recorded (rarely) on the south-west coasts of the British Isles in the mossy cracks of coastal rocks and sometimes in damp coastal heaths.
N.B. To be looked for in France because it is very similar to Cladonia furcata s.l. and probably confused with it, if it exists.
Two known chemotypes:
Chemo I: Fumarprotocetraric acid.
Chemo II: Fumarprotocetraric acid and bourgeanic acid.