Keys to the macrolichens and checklist of the lichens and ...

5b. Erect thallus solid, without cups and squamules; granular, peltate or finger-like;
phyllocladia often sessile, wrinkled to convoluted, pale brown to blackish
cephalodia present; ascospores septate ................................................. Stereocaulon
6a. Thallus flattened, strap-shaped, distinctly dorsiventral (with differently coloured
upper and lower surface); algae concentrated near the upper surface only ............. 7
6b. Thallus not flattened, terete or, if flattened, algae distributed on both lower and
upper sides ............................................................................................................. 10
7a. Thallus of straps; marginal cilia present .................................................................. 8
7b. Thallus of combs; marginal cilia absent .................................................................. 9
8a. Lower surface not corticate..................................................................Heterodermia
8b. Lower surface corticate.........................................................................Everniastrum
9a. Algae blue-green.....................................................................................Dictyonema
9b. Algae green ..........................................................................................Coenogonium
10a. Thallus gelatinous, dark green- to brown-black or black; photobiont blue-green. 11
10b. Thallus not gelatinous, colour various; photobiont various................................... 12
11a. Thallus without an upper cortex (microscope); thallus usually brown- or greenblack..............................................................................................................Collema
11b. Thallus with an upper cortex consisting of a single layer of cells (microscope);
thallus usually blue-grey, brown or grey-black ........................................ Leptogium
12a. Thallus with blue-green algae, to c. 1 cm tall, consisting of very slender, minutely
tufted, spreading filaments..................................................................................... 13
12b. Thallus with gren algae, c. 1-20 cm tall, filamentous or otherwise ....................... 15
13a. Thallus richly branched, ± erect, brown to black................................................... 14
13b. Thallus little branched, ± decumbent; blue-green if erect ......................Dictyonema
14a. Surface shiny; surface cells mosaic-forming ......................................... Polychidium
14b. Surface matt, tomentose near the base; surface cells rounded.
................................................... Dendriscocaulon (unidentifiable morphs of Sticta)
15a. Thallus and/or soralia C+ red; exclusively coastal, firmly attached to rock or bark,
coastal; photobiont Trentepohlia................................................ Roccella montagnei
15b. Thallus and soralia (if present) C–; ecology various ............................................. 16
16a Thallus filamentous, with a tough axial strand, not easily broken when branches are
. pulled; ascospores simple ................................................................................ Usnea
16b. Thallus filamentous or otherwise, without a tough, axial strand (breaking cleanly
when pulled apart).................................................................................................. 17
17a. Thallus thread-like, with thin, often pointed, apices.............................................. 18
17b. Thallus not thread-like, apices mostly blunt.......................................................... 19