Key to major genera

1. Spores distinctly coloured in mass and coloured individually under the microscope [2]
Spores not, or faintly, coloured in mass and hyaline under the microscope [25]
2. Spores blackish or some shade of brown [8]
Spores pinkish [3]
3. Stem laterally attached to the cap or absent Claudopus (and some species of Clitopilus)
Stem centrally attached to the cap [4]
4. Stem with a cup-like structure enveloping the base Volvariella
Stem lacking any special structure at its base [5]
5. Gills not attached to the stem (free), or with part attached to and descending down the stem (decurrent) [6]
Gills attached to the stem but not descending down the stem [7]
6. Gills remote to free from the stem Pluteus
Gills distinctly attached and descending down the stem Clitopilus (see also Eccilia [p. 102])
7. Gills broadly attached to the stem (adnate) Entoloma
Gills narrowly attached to the stem (adnexed) Leptonia & Nolanea
8. Stem laterally attached to the cap Crepidotus
Stem centrally attached to the cap [9]
9. Spore-print some shade of brown [10]
Spore-print blackish to purplish black [18]
10. Spore-print bright rust-brown [11]
Spore-print dull clay-brown or ochraceous [16]
11. Stem with the veil girdling the stem (ring), or cobweb-like (cortina) [12]
Stem without the veil girdling the stem or when present then easily lost [13]
12. Stem with distinct ring or ring-zone Pholiota & related genera
Stem with cobweb-like veil or faint filamentous ring-zone Cortinarius & Gymnopilus
13. Gills attached to the stem but not descending down the stem (adnexed to adnate) [14]
Gills free of the stem, or distinctly attached to and running down the stem (decurrent), and then often joined together at the apex of the stem or at their base [15]
14. Cap-surface composed of rounded cells Conocybe
Cap-surface composed of filamentous cells Galerina
15. Gills free of the stem and the whole fruit-body very fragile Bolbitius
Gills attached to and running down the stem (decurrent), easily separable from the cap-tissue and frequently veined at apex of stem Paxillus
16. Cap scaly, fibrillose and roughened Inocybe
Cap smooth, greasy or viscid [17]
17. Cap-surface composed of rounded cells Agrocybe
Cap-surface composed of filamentous cells Naucoria & Hebeloma
18. Gills or complete fruit-body becoming liquefied Coprinus
Neither the gills nor fruit-body collapsing into a slurry of cells [19]
19. Gills free to remote from the stem or attached and descending down the stem (decurrent) [20]
Gills attached in some way to the stem but not descending down the stem (adnate to adnexed) [21]
20. Gills decurrent; stem possessing a cobweb-like veil Gomphidius and Chroogomphus
Gills remote or free; stem possessing a usually persistent ring Agaricus
21. Gills distinctly spotted or distinctly mottled; stem stiff but breaking with a snap when bent; growing on dung or in richly manured areas Panaeolus
Gills not spotted or distinctly mottled; stem cartilaginous or not, and fruit-body growing on dung or not [22]
22. Gills broadly attached to the stem (adnate) and with a veil girdling the stem Stropharia
Gills narrowly attached to the stem (adnexed) or with concave dentation near the stem (sinuate), or if adnate then lacking a ring [23]
23. Gills with concave indentation near the stem (sinuate) and cap and stem with a cobweb-like veil Hypholoma
Gills attached to the stem but lacking a distinct concave indentation near the stem [24]
24. Stem stiff but breaking with a snap when bent; edge of cap incurved at first and cap-surface composed of filamentous cells Psilocybe
Stem fragile; edge of cap straight even when young and cap-surface composed of rounded cells Psathyrella
25. Fruit-body fleshy and readily decaying, often firm but never tough [26]
Fruit-body tough and not easily decaying [47]
26. Parasitic on other agarics Nyctalis
Not parasitic on other agarics [27]
27. Spore-bearing layer on fold-like often forked gills or simply on irregularities [28]
Spore-bearing layer (hymenium), on distinct well-formed gills [29]
28. Spore-bearing layer on fold-like gills Cantharellus
Spore-bearing layer on surface of irregularities Craterellus
29. Cap easily separable from the stem [30]
Cap not easily separable from the stem [31]
30. Stem with girdling veil (ring) and/or with a persistent cup-like structure at the base (volva); cap usually with warts or scales distributed on its surface Amanita
Stem with a ring but lacking a volva; cap surface powdery, hairy or scaly Lepiota & related genera
31. Cap, stem and gills brittle; stem never stiff and either exuding a milk-like juice or not; spores with spines or warts which stain blue-black in solutions containing iodine [32]
Cap, stem and gills soft or if stem stiff then snapping when bent; gills never brittle [33]
32. Fruit-body exuding a milk-like fluid Lactarius
Fruit-body not exuding milk-like fluid Russula
33. Gills thick, watery and lustrous (waxy) or with a bloom as if powdered with talc; often brightly coloured [34]
Gills not waxy and rarely over 1·5 mm thick [36]
34. Gills rather watery and lustrous (waxy); spores smooth [35]
Gills rigid not watery, with powdery bloom; spores with distinct spines Laccaria
35. Fruit-body with a distinct veil and growing in woods; cap often viscid or pale coloured Hygrophorus
Fruit-body lacking a veil and usually growing in fields; cap usually brightly coloured and sometimes viscid Hygrocybe
36. Stem with girdling veil (ring) and/or stem not attached to the centre of the cap (eccentric) [37]
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
Stem not attached to the centre of the cap and fruit-body although persistent not easily revived to natural shape after once being dried [48]
48. Spore-print blue-black with solutions containing iodine [49]
Spore-print yellowish in solutions containing iodine [50]
49. Gills toothed or notched along the edges Lentinellus
Gills even along their edges and not toothed Panellus
50. Gills appearing as if split down their middles Schizophyllum
Gills not splitting [51]
51. Gills notched or toothed along their edges Lentinus
Gills even along their edges and not toothed Panus
52. Spore print yellowish, purplish, black or pink [53]
Spore-print some shade of brown, but without purplish flush [56]
53. Spore-print yellowish or pinkish [54]
Spore-print purplish brown or blackish [55]
54. Spore-print yellowish Gyroporus
Spore-print pinkish Tylopilus
55. Spore-print purplish brown Porphyrellus
Spore-print blackish and spores ornamented Strobilomyces
56. Cap glutinous and stem with or without girdling veil (ring); within the tubes the sterile cells (cystidia) cluster together Suillus
Cap at most viscid and then only in wet weather and sterile cells within the tubes individually placed [57]
57. Stem-surface covered with distinct black or dark brown or white then darkening scales; spore-print clay-brown with or without a flush of cinnamon-pinkish brown Leccinum
Stem-surface covered completely or in part with a network or pattern of faint lines or pale yellow or red-rust but never black dots; spore-print olivaceous buff Boletus & related genera