Stem central and lacking a ring 38 37. Stem central and possessing a ring _Armillaria_ Stem not centrally attached to the cap members of the ‘_Pleurotaceae_’ (p. 74) 38. Stem fibrous 39 Stem stiff only in the outer layers 42 39. Gills with a concave indentation near the stem (sinuate) 40 Gills attached to and descending down the stem (decurrent) 41 40. Spores with warts which darken in solutions containing iodine _Melanoleuca_ Spores not so colouring in solutions containing iodine _Tricholoma_ & related genera 41. Spores with warts which darken in solutions containing iodine _Leucopaxillus_ Spores not so colouring in solutions containing iodine _Tricholoma_ & related genera 42. Gills thick and with rather blunt edges _Cantharellula_ & _Hygrophoropsis_ Gills thin and with distinct and sharp edges 43 43. Gills attached to and descending down the stem (decurrent); cap often depressed at the centre and sterile cells absent from the gills and the surface of the cap _Clitocybe_ & _Omphalina_ Gills attached to the stem but not descending down the stem (adnate to adnexed) or if descending then distinct sterile cells on the gills, cap and stem 44 44. Cap-edge straight and usually striate when young; cap thin and somewhat conical and gills descending down the stem or not _Mycena_ & related genera Cap-edge incurved, non-striate and cap rather fleshy; gills not descending down the stem 45 45. Stem dark and woolly at least in the lower half and the cap viscid; fruit-bodies growing in clusters on tree-trunks _Flammulina_ Stem not dark and woolly 46 46. Cap viscid and stem usually rooting; fruit-body growing directly on wood or attached to wood by long strands or cords of mycelium (rhizomorphs) _Oudemansiella_ If cap viscid then fruit-body neither attached to wood by cords of mycelium nor stem with a rooting base _Collybia_ & related genera 47. Stem central and gills often interconnected by veins; cap can be dried and later revived, purely by moistening _Marasmius_ & related genera