Chapter II: Introduction (1)

The term larger fungus refers to any fungus whose study does not necessarily require more than a low-powered lens to see most of the important morphological features. Using such a term cuts across the existing scientific classification, for it includes the more obvious fungi bearing their spores on specialised reproductive cells called basidia, fig. 5, and a few of those whose spores are produced inside specialised reproductive cells called asci. The term is useful, however, even though it embraces a whole host of unrelated groups of fungi; it includes the polypores, fairy-clubs, hedgehog-fungi, puff-balls and elf-cups, as well as the more familiar mushrooms and toadstools--or puddockstools as they are often called in Scotland. Specimens of all these groups will find their way some time into the collecting baskets of the naturalist when he is out fungus-picking, along with probably a few jelly-fungi and less frequently one or two species of the rather more distantly related group, the morels. The biggest proportion of the finds, however, on any one collecting day in the autumn, when the larger fungi are in their greatest numbers, will be of the mushrooms and toadstools; these are, collectively, more correctly called the agarics.

The early botanists and pioneer mycologists of the nineteenth century recognised the fact that the fungi both large and small are ecologically connected to the herbaceous plants and trees among which they grow, but many mycologists since have tended to neglect these early observations. Although the importance of the fungi in the economy of the woodland, copse, field and marsh is well-known, mycologists and ecologists alike have been rather slow to appreciate that the fungi can be just as good indicators of soil conditions, if not better, than many other plants. Perhaps it is rash to attempt such a treatment as you find here because we know so little of the reasons why a particular fungus prefers one habitat to another. However, it is envisaged and hoped that, if a framework is provided, accurate field-notes can gradually be accumulated and many of the secrets yet to be uncovered explained.

_Where to look_

Fungi can be found in most situations which are damp at some time of the year. Searching for fungi can begin as soon as the spring days become warm, although even in the colder periods of winter several finds can be made. In summer it gets very dry and this necessitates collecting in damper areas, such as marshes, alder-carrs, swamps and moorland bogs. After a heavy storm in summer, on the edges of paths and roadsides, woodland banks, in clearings in woods and in gardens, fungi can be collected within a few days of the rain, but collecting normally reaches a climax in August-September, the precise date depending on the locality and the individual character of the particular year.

All woodlands are worth visiting, particularly well-established woods with a mixture of trees. Pure pine-woods do not seem to be as good as pine-woods with scattered birch; plantations are often disappointing except after heavy rain or late in the season, even well into November in mild years. Pure birch and beech, the latter particularly when on chalky soils, are excellent areas to visit. Oak is possibly not as good but areas with willow and alder have many unique species. The edge of woods, sides of paths or clearings are usually more productive areas to search in than is the depth of the wood, and a small plot of trees can be much more rewarding than a large expanse of woodland. After some time one is able to judge the sort of place which will yield fungi. Rotten and burnt wood are very suitable substrates for they retain the moisture necessary for growth of fungi even in dry conditions, so allowing fructification to take place.

Grasslands including hill-pastures, established sand-dunes, etc., are often excellent, but of course they are much more dependent on the weather to produce favourable conditions for fungal development than woodland areas where the changes in the humidity and temperature are less extreme; prolonged mist or mild showery weather favour the fruiting of the grassland fungi. Dung in both woods and fields is an excellent although ephemeral substrate; many species of fungi characterise dung whilst others will grow in manured fields, on straw-heaps or where man has distributed the habitat.

_Collecting_

The collecting of larger fungi should not be considered a haphazard pursuit; careless collecting often results in many frustrating hours being spent on the identification of inadequate material, which is also not suitable after for preservation as reference material. A few good specimens are infinitely better than several poor ones; one is always tempted to collect too much and then collections are inevitably discarded. Always try to select specimens showing all the possible stages of development from the smallest buttons to the expanded caps. Sometimes such a range is not possible and one must be satisfied with either a couple or only one fruit-body.

Carefully dig up or cut from the substrate the entire fungus and handle it as little as possible. A strong pen-knife or fern-trowel is admirable for the job. The associated plants should be noted, especially trees, and if one is unable to identify the plants or woody debris retain a leaf or a piece of wood for later identification. One should note in a field-notebook any features which strike one as of interest, such as smell, colour, changes on bruising, presence of a hairy or viscid surface.

For transporting home the specimens should be placed in tubes, tins or waxed paper which are themselves kept in a basket. The smallest specimen can go in the first, the intermediate-sized forms in the tins or waxed paper and the larger ones laid in the basket or placed in large paper bags; plastic bags are not suitable except for very woody fungi. Thus an assortment of tins, tubes and various sizes of pieces of waxed paper are essential before setting out on a collecting trip. The specimens should be placed in the waxed paper such that they can be wrapped once or twice and the ends twisted as if wrapping a sweet.

_Examination_

_Once home always aim at examining the specimens methodically._

The first necessity is to determine whether the fungus, which has been collected, has its spores borne inside a specialised reproductive cell (ascus) i.e. Ascomycete, or on a reproductive cell (basidium) i.e. Basidiomycete. By taking a small piece of the spore-bearing tissue, mounting in water, gently tapping it and examining under a low power of the microscope this can be easily ascertained. The tapping out is best done with the clean eraser of a rubber-topped pencil. There are several different shaped asci and basidia; the latter structures are more important in our study because the Ascomycetes are in the main composed of microscopic members.

The following procedure is necessary for the examination of your find:--

Select a mature cap of an agaric from each collection, cut off the stem and set the cap gills down on white paper, or if the specimen is small or is a woody or toothed fungus, or consists of a club or flattened irregular plate, place the spore-bearing surface (hymenium) face down on a microscope glass slide. The smaller specimens must be placed in tins with a drop of water on the cap to prevent drying out. Even with the larger specimens it is desirable to place a glass slide somewhere under the cap between the gills and the paper, and if possible to enclose the species carefully in waxed paper or in a tin. Whilst you are waiting for the spore-print to form, notes must be made on the more easily observable features; one is not required at this stage to examine the microscopic characters.

All the characters which may change on drying must be noted immediately, and these include colour, stickiness, shape, smell and texture. A sketch, preferably in colour, however rough, can give much more information than many score words.

Cut one fruit-body, longitudinally down with a razor or scalpel or a sharp knife if the fruit-body is woody, and sketch the cut surfaces, fig. 1A-B. These sketches and the rest of the collection notes should be made such that identification and future comparisons can be achieved. Thus always note the characters in the same order for each description. A table of the important characters is provided here, but this is meant as a guide not as a questionnaire. The attachment of the gills, pores or teeth to the fruit-bodies when once the fungus is in section should be always noted (see p. 20).

The spore-print when complete should be allowed to dry under normal conditions and then the spore-mass scraped together into a small pile. A microscope cover-slip should be placed on the top of the pile and lightly pressed down. The colour of the spore-print (or deposit) can then be compared with a standard colour chart and the spores making up the print examined in water under a microscope.

_Microscopic examination_

When one is more experienced with fungi it will be found necessary to carry out many microscopic observations, but when commencing the study it is necessary only to have an ordinary microscope; a calibrated eyepiece-micrometer is an advantage as is an oil-immersion lens. An examination of the spores is always necessary; the examination of features such as the sterile cells on the gill and stem, etc., varies with the fungus under observation. Spores should if at all possible be taken from a spore-print and mounted on a microscope slide, either in water or in a dilute aqueous solution of household ammonia. Although for mycologists it is often necessary to measure spores to within a ½ micron (µm) this book has been so arranged that one only really has to distinguish between a spore which is small (up to 5 µm), medium (5-10 µm), long (10-15 µm), or large if globose and very long (if over 15 µm); this is not strictly accurate, but serves the purpose for an introductory text. It is important to describe the character of the spore, i.e. ornamentations, whether a hole (germ-pore) is present at one end and/or a beak (apiculus) at the other (fig. 5). With white or pale coloured spores it is useful to stain either the spore or the surrounding liquid with a dye--10% cotton blue solution is admirable, or a solution of 1·5 g iodine in 100 ml of an aqueous mixture containing 5 g of potassium iodine and 100 g of chloral hydrate. Both these dyes must be accurately made up if the study of the fungi is to be taken at all seriously; because some of the chemicals used above are not normally required by students, a chemist must make up the reagents for you. Often the spores turn entirely or partially blue-black or pale blue or purplish red in the iodine solution--a useful character.

Material in good condition is always required and one of the first things the student needs to do is train himself to collect sufficient material in good condition. The steps by which all the structures of the fungus used in the text can be observed are outlined below:--

Fig. 1 shows the cuts required to furnish suitable sections in order to observe the various structures and patterns of tissue which are important.

1. Carefully place the longitudinal section (AB) of the fruit-body which has been sketched gill-face down under a low power or dissecting microscope. Hairs or gluten on the cap, if present, will be made visible by focusing up and down (figs. 2 and 3A) and/or those on the stem (fig. 3B). When any part of the cut fruit-body is not being examined retain it in a chamber containing damp paper or moist moss; this will assist the cells to retain their turgidity, for they frequently collapse on drying and are difficult to observe except after performing often lengthy and special techniques.

If only one fruit-body is available, then cut along CD and mount in a tin box on a slide in order to obtain a spore-print (otherwise see paragraph 6).

2. Cut off a complete gill (E) and quickly mount on a dry slide. Under the low power of a microscope, the cystidia on the gill-margin will be visible (fig. 4); it will be seen whether the spores are arranged in a particular pattern (fig. 5) and whether the basidia are 2-spored or 4-spored. In white-spored toadstools it is difficult sometimes to determine whether the basidia are 2- or 4-spored so one must confirm the observations by other techniques.

Fig. 3.

Fig. 4.

Fig. 5.

Fig. 6.]

A section of the gill accompanied by a small piece of cap-tissue, as in E, will confirm the presence or absence of noticeable cystidia (or hairs) on the cap. Now mount the section bounded by FG and HI in a drop of water containing either a drop of washing-up liquid and/or glycerine; the soapy liquid helps to expel any water which may tend to cling to the gill-margin amongst the cystidia and the glycerine stops the mount from drying out whilst further sections for comparison are cut and examined. It is at this time that the structure of the outermost layer of the cap can be examined, e.g. whether it is made up of a turf-like structure; the presence or absence of cystidia on the cap can be also confirmed (fig. 7A-C). It is frequently necessary to tap the mount in order to spread the tissue slightly and expose the elements; this can be done very efficiently by light pressure from the end of a pencil to which an eraser is attached. Cut off along line JK to eliminate marginal cystidia from confusing the picture and mount both pieces separately.

3. Cut out a wedge of tissue from the fruit-body (L) so as to have several gills attached to some cap-tissue; until one is familiar with the variability of facial and marginal cystidia, carefully cut along the line PQ (note: the cut is made one-third of the distance from the cap margin, thus eliminating the possibility of large numbers of marginal cystidia being examined in error for facial cystidia). Now make a second cut along the line of RS so that finally a small block of tissue remains (M).

Mount on a dry slide with the plane through PQ face down on the slide and observe under a low magnification, to assess whether cystidia on the gill-face are present or absent, and if present their general shape and whether numerous or infrequent (fig. 8).

Mount in water/washing-up mixture as outlined above and tap gently with the rubber attached to the end of a pencil; evenly distributed pressure should be given. If the gills appear to be too close then rotate the rubber a little whilst pressing in order to spread the tissue.

4. Using a low power of a microscope and looking down into the plane RS of the unmodified block M or a similar block, one obtains by this simple technique a very accurate idea as to the structure of the trama of the gill (fig. 9). The organisation of this tissue is very important in classification, some groups of toadstools having what has been described as regular trama (fig. 9C), others irregular (fig. 9D), inverse (fig. 9B) or divergent (fig. 9A). This same tissue may be thick or sparse to wanting, coloured or not. Such sections are often better than attempts at very thin sections unless very specialised techniques are used. There are few satisfactory thicknesses between the two extremes; the thick sections you can do and the very thin requiring expert techniques.

Fig. 8.

Fig. 9.

Fig. 10.]

5. Take out a small block of tissue T as indicated in the figure (fig. 1). Mount immediately and repeat as in 3. This will allow the outer layer of the cap to be more clearly seen (fig. 7A-C) and also the structure of the flesh (fig. 10). The latter may be composed of a mixture of filaments and ‘packets’ or ‘nests’ of rounded cells (i.e. heteromerous), or of filaments, only some of which may be inflated (i.e. homoiomerous); but when individual cells are swollen they never form distinct groups. By very similar techniques it is possible to show that the more woody fungi can have flesh composed of one of four types of cells (Corner, 1932): these types depend on whether distinctly thickened cells (plate 47) are present with the actively growing hyphae or not (pp. 140-150), whether hyphae are present which bind groups of hyphae together, etc. (plate 46).

6. Remove stem along line CD and cut out small blocks of tissue as indicated (U, V and W). Mount immediately and examine as in paragraph 3, for cystidia, etc. (see fig. 3).

Whilst all these sections are being cut and processed a second fruit-body, if available, should be set to drop spores; this is done by cutting off the cap from the stem and placing it either entirely or in part, and with gill-edges down, on a slide in a tin.

7. Z is a ‘scalp’ of a cap; a thin sliver from the cap is placed on a slide in a drop of water (modified with washing-up liquid, etc. as above). After placing a cover-slip over the tissue it is tapped gently; this will show if the cap is composed of globose to elliptic elements or if it is composed of strictly filamentous units (figs. 6A & B). Care must be taken not to reverse the section when transferring it to the mountant, either by turning the scalpel or by allowing the surface tension of the liquid to pull the section upside down. The construction of any veil fragments will also be seen in this mount, and if a loose covering of veil is present this should be removed before observation so that it does not obscure the fundamental structures.

8. Examine the stipe of the fruit-body used above under a low power or with a dissecting microscope in order to ascertain whether there are any remains of veil and/or vegetative mycelium. If found, mount immediately in the solution containing iodine mentioned above and examine.

Of course it is difficult to carry out the above system the first time and be successful in seeing everything, indeed in being able to cut all the sections 1-8. Practice makes perfect, so why not practise with a ¼ lb of mushrooms from the grocer before the autumn season starts. In this way you will have overcome the difficulties without having to experiment with your collections.

CHARACTERISTICS FOR THE IDENTIFICATION OF HIGHER FUNGI WITH CAPS
Locality G. Ref. Date
Habitat notes soil type pH
vegetational community
solitary; in troops or rings
Draw or preferably paint exterior and vertical section of fruit-body
MACROSCOPIC CHARACTERS
CAP
General characters:
diameter shape consistency
colour: when immature when mature
when wet when dry
Surface
dry, moist, greasy, viscid, glutinous, peeling easily or not,
smooth, matt, polished, irregularly roughened, downy, velvety,
scaly, shaggy
Margin
regular, wavy incurved or not
smooth, rough, furrowed striate or not
Veil, if present
colour abundance or scarcity
distribution at margin, whether appendiculate or dentate
consistency, whether filamentous, membranous
GILLS, or pores or teeth etc.
remote, free, adnate, adnexed, emarginate, subdecurrent, decurrent
crowded or distant distinctly formed or not
shape interveined or not
easily separable from the cap-tissue or not
consistency (whether brittle, pliable, fleshy or waxy)
thickness width
colour: when immature at maturity
number of different lengths or number of layers
obvious features of gill-edge, tube-edge, e.g. colour, consistency
STEM
central, eccentric or lacking shape
dimensions: length thickness
hollow or not
colour: when immature when mature
consistency (whether fleshy, stringy, cartilaginous, leathery or
woody)
surface characters (whether fibrillose, dry, viscid, scaly or
smooth)
characters of stem-base
Veil, if present characters
Volva, if present characters
Ring, if present
whether single or double whether membranous or filamentous
whether persistent, fugacious or mobile whether thick or thin
whether apical, median or basal
FLESH
colour in cap: when wet when dry
colour in stem: when wet when dry
colour changes if any when exposed to air
presence or absence of milk-like or coloured fluid
(note: colour when exuded on fruit-body immediately and after some
time and when dabbed on to a clean cloth or paper handkerchief and
exposed to the air).
SMELL before and after cutting --relate to a common every day odour
MICROSCOPIC CHARACTERS
BASIDIOSPORES
colour in mass colour under microscope.
shape size type of ornamentation, if any
size and shape of germ-pore, if present
iodine reaction of spore-mass:--blue-black to dark violet
(amyloid); red-purple (dextrinoid); yellow-brown or brown
(non-amyloid)
BASIDIA number of sterigmata
CAP-FLESH type of constituent cells
GILL-TISSUE type and arrangement of cells between adjacent
hymenial faces
CAP-SURFACE type of cells composing the outermost layer--whether
filaments or rounded cells
STERILE CELLS--CYSTIDIA
presence or absence of sterile cells:--
on gill-edge on gill-margin
on cap on stem
shape, estimation of size, thick or thin-walled, hyaline or not
types of ornamentation, etc.

Key to the major classes of Larger Fungi

Spores borne externally on stalks on a clavate to cylindrical cell
Basidiomycotina
Spores produced within a clavate, cylindrical or subglobose cell
Ascomycotina

Key to major groups based on character of basidium and fruit-body shape

1. Basidia either produced in a hymenium or in a mass, and until
maturity contained within a closed fruit-body Gasteromycetes

Basidia produced in a layer of cells (hymenium) and exposed to the
air before the maturity of the spores (Hymenomycetes) 2

2. Basidia simple, a single cell (fig. 5) (Homobasidiae) 3

Basidia usually septate, or if simple then fruit-body gelatinous
and often collapsing to form a skin when dried (Heterobasidiae) 4

3. Fruit-body usually fleshy, soft and easily decaying (putrescent),
hymenium spread over the surface of gills, ridges or within tubes
Agaricales (p. 22)

Fruit-body with hymenium smooth or spread-out on teeth, ridges or
plates or if within tubes then fruit-body tough and leathery
Aphyllophorales (p. 135)

4. Basidia divided 5

Basidia simple and apex drawn out into two long necks Plate 61 (p.
185) Dacrymycetales (p. 180)

5. Basidia divided transversely by one to three horizontal septae
Plate 60 (p. 183) Auriculariales (p. 182)

Basidia divided into two or four cells by vertical septae Plate 61
(p. 185) Tremellales (p. 184)

A. AGARICS AND THEIR RELATIVES

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

(i) Agarics of woodlands and copses

(a) Mycorrhizal formers

~Leccinum scabrum~ (Fries) S. F. Gray

Birch rough stalks or Brown birch-bolete.

_Cap_: width 45-150 mm. _Stem_: length 70-200 mm; width 20-30 mm.

_Description_: Plate 1.

Cap: convex and becoming only slightly expanded at maturity, pale
brown, tan or buff, soft, surface dry, but in wet weather becoming
quite tacky, smooth or streaky-wrinkled and cap-margin not overhanging
the tubes.

Stem: white, buff or greyish, roughened by scurfy scales which are
minute, pale and arranged in irregular lines at the stem-apex, and
enlarged and dark brown to blackish towards the base.

Tubes: depressed about the stem, white becoming yellowish brown at
maturity, with small, white pores which become buff at maturity and
bruise distinctly yellow-brown or pale pinkish brown when touched.

Flesh: watery, very soft in the cap lacking distinctive smell and
either not changing on exposure to the air or only faintly becoming
pinkish or pale peach-colour.

Spore-print: brown with flush of pinkish brown when freshly prepared.

Spores: very long, spindle-shaped, smooth, pale honey-coloured under
the microscope and more than 14 µm in length (14-20 µm long × 5-6 µm
broad).

Marginal cystidia: numerous and flask-shaped. Facial cystidia: sparse,
similar to marginal cystidia.

_Habitat_ & _Distribution_: Found in copses and woods containing birch
trees, or even accompanying solitary birches.

_General Information_: This fungus is recognised by the pale brown
cap, the white, unchanging or hardly changing flesh and the cap-margin
not overhanging the tubes. There are several closely related fungi
which also grow with birch trees but they need some experience in
order to distinguish them. This fungus was formerly placed in the
genus _Boletus_, indeed it will be found in many books under this
name. Species of _Leccinum_ are edible and considered delicacies in
continental Europe. The majority can be separated from the other
fleshy fungi with pores beneath the cap, i.e. boletes, by the black to
brown scaly stem and rather long, elongate spores. The scales on the
stem give rise to the common name ‘Rough stalks’ which is applied to
this whole group of fungi.

_Illustrations_: F 39C; Hvass 253; LH 122; NB 155⁶; WD 89¹.

~Suillus grevillei~ (Klotzsch) Singer

Larch-bolete

_Cap_: width 30-100 mm. _Stem_: width 15-20 mm; length 50-70 mm.

_Description_: Plate 2.

Cap: convex or umbonate at first, later expanding and then becoming
plano-convex, golden-yellow or rich orange-brown, very slimy because
of the presence of a pale yellow sticky fluid.

Stem: apex reddish and dotted or ornamented with a fine network,
cream-coloured about the centre because of the presence of a ring
which soon collapses, ultimately appearing only as a pale yellow zone;
below the ring the stem is yellowish or rusty brown, particularly when
roughly handled.

Tubes: adnate to decurrent, deep yellow but becoming flushed
wine-coloured on exposure to the air, with angular and small
sulphur-yellow pores which become pale pinkish brown to lilaceous or
pale wine-coloured when handled.

Flesh: with no distinctive smell, pale yellow immediately flushing
lilaceous when exposed to the air, but finally becoming dingy
red-brown, sometimes blue or green in the stem-base.

Spore-print: brown with distinct yellowish tint when freshly prepared.

Spores: long, ellipsoid, smooth and pale honey when under the
microscope, less than 12 µm in length (8-11 µm long × 3-4 µm broad).

Marginal cystidia: in bundles and encrusted with amorphous brown, oily
material. Facial cystidia: similar in shape and morphology to marginal
cystidia.

_Habitat_ & _Distribution_: Found on the ground accompanying larch
trees either singly or more often in rings or troops.

_General Information_: This fungus is easily recognised by the poorly
developed ring, overall golden-yellow colour and pale yellow
viscidness on the cap which comes off on to the fingers when the
fruit-body is handled. There are several closely related fungi
which also grow with coniferous trees, e.g. _Suillus luteus_ Fries,
‘Slippery jack’, but many need experience in order to identify them.
All these fungi were formerly placed in the genus _Boletus_, because
of the fleshy fruit-body with pores beneath the cap. The larch-bolete
receives its common name from the close relationship of the fungus
with the larch. On drying _S. luteus_ and _S. grevillei_ may strongly
resemble one another but the former can be distinguished when fresh by
the chocolate brown, sepia, or purplish brown cap and the large
whitish, lilac-tinted ring.

Species of _Suillus_ are edible and rank highly in continental
cook-books, although they have disagreeably gelatinous-slimy caps, a
character, in fact, which helps to separate them from other fleshy
pore-fungi.

_Illustrations_: F 41a; Hvass 257; ML 187; NB 104⁴; WD 84².

~Boletus badius~ Fries

Bay-coloured bolete

_Cap_: width 70-130 mm. _Stem_: width 34-37 mm; length 110-125 mm.
(36-40 mm at base).

_Description_: Plate 3.

Cap: hemispherical, minutely velvety, but soon becoming smooth and
distinctly viscid in wet weather, red-brown flushed with date-brown
and darkening even more with age and in moist weather to become
bay-brown.

Stem: similarly coloured to the cap but paler particularly at the
apex, smooth or with faint, longitudinal furrows which are often
powdered with minute, dark brown dots.

Tubes: adnate or depressed about the stem, lemon-yellow but
immediately blue-green when exposed to the air and with angular,
rather large similarly coloured, pores which equally rapidly turn
blue-green when touched.

Flesh: strongly smelling earthy, pale yellow but becoming pinkish in
centre of the cap, and blue in the stem and above the tubes when
exposed to the air, but finally becoming dirty yellow throughout.

Spore-print: brown with a distinct olivaceous flush.

Spores: long, spindle-shaped, smooth, honey-coloured under the
microscope and greater than 12 µm in length (13-15 µm long × 5 µm
broad).

Marginal cystidia: numerous, flask-shaped and slightly yellowish.

Facial cystidia: scattered and infrequent and similar to marginal
cystidia in shape.

_Habitat_ & _Distribution_: Found in woods, especially accompanying
pine trees, but often found fruiting on the site of former coniferous
trees, even years after the trunks or the stumps have been removed.

_General Information_: This fungus is recognised by the rounded,
red-brown cap, coupled with the pale yellow flesh and greenish yellow
tubes, both of which become greenish blue when exposed to the air.
There are several species in the genus _Boletus_ which stain blue at
the slightest touch or when the flesh is exposed to the air, e.g. _B.
erythropus_ (Fries) Secretan, a common bolete with a dark olivaceous
cap, orange pores and red-dotted stem.

The flesh of some species of _Boletus_, e.g. _B. edulis_ Fries,
however, remains unchanged or at most becomes flushed slightly
pinkish. Although many people say they recognise _B. edulis_, the
‘Penny-bun’ bolete--a name derived from the colour of the cap, there
is some doubt as to whether the true _B. edulis_ is common in Britain
as we are led to believe. _B. edulis_ and its relatives are highly
recommended as edible (see p. 35). _B. badius_ is also edible, but it
is ill-advised to eat any bolete which turns blue when cut open.

_Illustrations_: _B. badius_--F 38c; Hvass 248 (not very good); LH
191; NB 109⁵; WD 85¹. _B. edulis_: F 42a; Hvass 246; LH 191; NB 143³.

General notes on Boletes

There are nearly seventy boletes recorded for the British Isles and evidence of others which have as yet not been fully documented. As a group they are characterised by being fleshy, possessing a central stem and producing their spores within the tubes, and not on gills as in the common mushroom. It is the first character by which the boletes differ so markedly from the other pored fungi, such as the ‘Scaly Polypore’ (see p. 140).

The boletes have long been classified in the genus _Boletus_, but instead of referring all the pored, fleshy fungi to a single large genus several genera are now recognised. The separation of these genera is based on differences in colour of the spore-print and differences in the anatomy of the tubes, cap and stem, etc., e.g. members of the genus _Suillus_ have colourless or pale coloured dots on the stem exuding a resin-like liquid in wet weather, which is clear and glistening in some species but turbid and whitish in others, gradually darkening and hardening so that the stem is ultimately covered in dark brown or reddish smears or spots; members of the genus _Leccinum_ on the other hand never exude liquid and have coarse or fine roughenings on the stem which are usually dark, but may commence white and ultimately darken depending on the species; many species of _Boletus_ possess a very distinct raised network all over the stem, whilst others have it present only in part, or have minute, often brightly coloured, dots replacing it.

Within this single, yet not particularly large, group of fungi, several biological phenomena are demonstrable. There is good evidence that the majority of British boletes are mycorrhizal; several species are known to be associated only with one species of tree or group of closely related tree-species. Thus _Suillus grevillei_ and _S. aeruginascens_ (Secretan) Singer grow in association with larch trees; _S. luteus_ and _Boletus badius_ in contrast grow in association with pine trees; _Leccinum scabrum_ with birch trees; _L. aurantiacum_ (Fries) S. F. Gray, with poplar trees and _L. quercinum_ (Pilát) Green & Watling, with oak trees.

_Boletus edulis_ can be separated into several distinct subspecies which are associated with different trees; the two commonest subspecies are those associated with birch and with beech trees. It is well known that although present in this country during the warmer periods of the Ice-Age, larch neither survived the intense cold of the last advance of the ice nor migrated back into Britain after the ice had melted. Thus all larches which we see in Britain have been planted by man. There is little doubt that mycelia of many fungi were introduced along with these plants very probably including the mycelium of the larch-bolete. A similar pattern can be seen with other introduced trees, although not to such a marked degree, e.g. spruce trees. The beech tree, however, is native to the south of England, unlike the larch returning to this country after the ice had melted; it has been planted extensively outside its former range in northern areas of the British Isles taking with it its associated fungi. There is some evidence that some stocks of beech and fungi have been introduced from continental Europe in comparatively recent times.

A parallel, yet inexplicable association is found between the bolete _Suillus bovinus_ (Fries) O. Kuntze and its close relative _Gomphidius roseus_ (Fries) Karsten where the mycelium of two fungi are found intertwined forming a close association! Parasitism although rare is also found amongst the boletes, and an uncommon parasitism at that--a fungus on a fungus; for example in Britain although infrequent _Boletus parasiticus_ Fries grows attached and ultimately replaces the spore-tissue of the common earth-ball (_Scleroderma_, see p. 192).

Those fungi which grow on dead and decaying substrates are called saprophytes and although the greater number of higher fungi would be included in this class of organisms the character is infrequent amongst the boletes. One British example of this type of fungus is the rare _Boletus sphaerocephalus_ Barla which grows on woody debris.

Chemists have long been interested in boletes, for as noted above the flesh of some species when exposed to the atmosphere turns vivid colours, a feature often incorporated into the Latin name, e.g. _Boletus purpureus_ Persoon, from the purple colours produced whenever the fruit-body is handled. The reaction appears to be an oxidation where in the presence of an enzyme and oxygen a pigmented substance or substances are produced. What the significance of these colour-changes is in nature is as yet unknown; however, what is interesting is that many of the chemicals involved are unique and have only recently been analysed completely; they are related to the quinones.

There is little doubt that it is this rapid and intense blueing of the flesh of many boletes that has lead to a belief that they are poisonous. It is uncertain whether there are any truly toxic species of _Boletus_ but several have unpleasant smells and tastes which make them very unattractive. _Boletus edulis_ is the important ingredient, however, which gives the distinctive taste to so-called dried mushroom soup. Thousands of fruit-bodies are collected annually in the forests of Europe to be later dried and processed for incorporation into soup. Boletes appear to form an important part of the diet of several rodents and deer and in Scandinavia in the diet of reindeer.

Probably one of the most obscure of our British boletes is _Strobilomyces floccopus_ (Fries) Karsten, the ‘Old Man of the Woods’. It has a black, white and grey woolly, scaly cap and stem, and the flesh distinctly reddens when exposed to the air. The spores are almost spherical, purple-black in colour and covered in a coarse network when seen under the microscope. All these characters readily separate _Strobilomyces_ from all other European boletes; however, in Australasia, members of this and related genera form a very important part of the flora.

~Chroogomphus rutilus~ (Fries) O. K. Miller

Pine spike-cap

_Cap_: width 30-150 mm. _Stem_: width 10-18 mm; length 60-120 mm.

_Description_:

Cap: convex with a pronounced often sharp umbo, wine-coloured, flushed
with bronze-colour at centre and yellow or ochre at margin, viscid but
soon drying and then becoming paler and quite shiny.

Stem: yellowish orange, apricot-coloured or peach-coloured, streaked
with dull wine-colour, spindle-shaped or narrowed gradually to the
apex from a more or less pointed base.

Gills: arcuate-decurrent, distant, at first greyish sepia then dingy
purplish with paler margin, but finally entirely dark purplish brown.

Flesh: lacking distinctive smell and reddish yellow or pale tan in the
cap, rich apricot- or peach-colour towards the stem-base.

Spore-print: purplish black.

Spores: very long, spindle-shaped, smooth, olivaceous purple and
greater than 20 µm in length (20-23 × 6-7 µm).

Marginal cystidia: cylindrical to lance-shaped and up to 100 × 15 µm.

Facial cystidia: similar to marginal cystidia.

_Habitat_ & _Distribution_: Found in pine woods, usually solitary or
in small groups. Fairly common throughout the British Isles and
characteristic of Scots Pine woods.

_General Information_: This fungus can be distinguished by the
purplish or wine-coloured cap and the gills being pigmented from
youth. There is only one other British species of this genus, i.e. _C.
corallinus_ Miller & Watling.

_Chroogomphus_ is separated from _Gomphidius_ by the flesh having an
intense blue-black reaction when placed in solutions containing
iodine, and the gills being coloured from their youth. In many books
_Chroogomphus_ is placed in synonymy with the genus _Gomphidius_.
However, _Gomphidius glutinosus_ (Fries) Fries, _G. roseus_ (Fries)
Karsten and _G. maculatus_ Fries all have whitish gills when immature
which gradually darken, and their flesh simply turns orange-brown in
solutions of iodine. _G. glutinosus_ is uniformly grey in colour and
is most frequently found under spruce and other introduced conifers:
_G. roseus_ has a pale-pinkish coloured cap and white stem, and grows
with pine; _G. maculatus_ grows under larch and is flushed lilaceous
at first but becomes strongly spotted with brown when handled.

_Illustrations_: Hvass 192; LH 213; WD 83^{a}.

~Paxillus involutus~ (Fries) Karsten

Brown roll-rim

_Cap_: width 50-120 mm. _Stem_: width 8-15 mm; height 30-75 mm.

_Description_:

Cap: at first convex with a strongly inrolled, downy margin, but then
expanded and later frequently depressed towards the centre,
clay-coloured, ochre or yellow-rust, slightly velvety but becoming
smooth or sticky particularly in wet weather and readily bruising
red-brown when fresh.

Stem: central or slightly eccentric, thickened upwards,
fibrillose-silky, similarly coloured to the cap but typically streaked
with red-brown particularly with age.

Gills: ochre or yellow-brown then rust and finally darker brown,
decurrent, crowded, often branched and united about the apex of the
stem; easily peeled from the flesh with the fingers and rapidly
becoming red-brown on handling.

Flesh: thick, soft and with slightly astringent smell and yellowish to
brownish but becoming red-brown after exposure to the air.

Spore-print: rust-brown.

Spores: medium-sized, ellipsoid, smooth, deep yellow-brown and rarely
greater than 10 µm in length (8-10 × 5-6 µm).

Marginal cystidia: numerous lance-shaped or spindle-shaped.

Facial cystidia: scattered and similar in shape to marginal cystidia.

_Habitat_ & _Distribution_: Found on heaths and in mixed woods,
particularly where birch has or is now growing, or even accompanying
solitary birch trees.

_General Information_: This fungus is easily recognisable by the
strongly inrolled, woolly margin of the cap and yellow-brown gills
which are easily separable from the cap-flesh. _P. rubicundulus_ P. D.
Orton is similar but grows under alder and has yellow gills unchanging
when handled and dark scales on the cap. _P. atrotomentosus_ (Fries)
Fries and _P. panuoides_ (Fries) Fries both grow on coniferous wood
and have smaller spores; the former is recognised by the dark brown to
almost black shaggy stem and the latter by the shell-shaped cap devoid
almost completely of a stem.

_Illustrations_: F 41c; Hvass 189; LH 185; NB 115⁸; WD 70².

~Cortinarius pseudosalor~ J. Lange

_Cap_: width 60-125 mm. _Stem_: width 15-25 mm; length up to 180 mm.

_Description_:

Cap: bell-shaped or bluntly conical only slightly expanding with
maturity, smooth or wrinkled at centre but often furrowed at the
margin, slimy, brown with a distinct olive flush when in fresh
condition and becoming ochraceous brown and shiny when dry.

Stem: usually swollen to some degree about the middle, slimy
particularly towards the base, whitish throughout when young except
for a faint amethyst or violaceous flush in the lower part; as the
slime dries the stem becomes shiny and the outer surface breaks up
into fibrillose scales or scaly, irregular ring-zones.

Flesh: lacking distinct smell, white with ochraceous flush in the cap,
white in the stem, thick and soft in the cap but fibrous in the stem.

Gills: adnate, broad, rather thick, frequently veined and distant,
ochraceous brown and finally deep rust-brown.

Spore-print: rust-colour.

Spores: long, slightly almond-shaped in side view, finely warted
throughout and not less than 12 µm in length (13-14 × 7-8 µm).

Marginal cystidia: ellipsoid or club-shaped, hardly different from the
surrounding undeveloped basidia.

Facial cystidia: absent.

_Habitat_ & _Distribution_: Found on the ground in copses and woods
especially those containing beech.

_General Information_: Recognised by the conical, grooved cap and the
slimy spindle-shaped stem with a distinct violaceous flush; this
fungus is often misnamed _C. elatior_ Fries but this is a much less
common fungus. There are several closely related fungi, but these grow
with other tree-species and need much more experience to distinguish
one from the other. _C. pinicola_ P. D. Orton is one such species
growing in the litter under _Pinus sylvestris_, Scots Pine; this
species is fairly common in the remnant pine woods of Northern
Scotland. The large size, sticky or glutinous cap and stem indicate
that this fungus belongs to _Cortinarius_, subgenus _Myxacium_.

_Illustrations_: Hvass 145; LH 162; NB 119; WD 60¹.

General notes on Cortinarii

The genus _Cortinarius_ is the largest genus of agarics in the British Isles, indeed in Europe and North America--perhaps in the world. It includes some of our most beautiful agarics, yet it is one of the least satisfying to the mycologist because of the difficulties experienced in identifying collections--partly because many species are so seldom seen.

_Cortinarius_ contains just under two hundred and fifty recognisable British species, although recent research has shown that many more are yet to be described from this country as new to science. Except for some very characteristic species the individual members within the genus _Cortinarius_ are often very difficult to separate one from the other; however, _Cortinarius_ is one of our least difficult genera to recognise in the field owing to the presence when mature of rust-coloured gills and a cobwebby veil which extends from the margin of the cap to the stem. This structure is termed a cortina (Fig. 14) and in young specimens covers the gills with delicate filaments. As the cap expands the cottony or cobwebby filaments are stretched and either disappear entirely or may collapse to form a ring-like zone of filaments on the stem. In some species a second completely enveloping veil is also found, and this veil is viscid in one distinct group of which _C. pseudosalor_ already described is a member. The gills in the genus are variable in colour when young although constant for a single species; they may be lilaceous purple, orange, brown, red, yellow-ochraceous or tan, but ultimately in all members at maturity they become rust-colour. The spores under the microscope are richly coloured, yellow to red-brown and are frequently strongly warted; in mass they are rust-brown and this character coupled with the presence of the cobweb-like veil characterises the genus.

Within the genus _Cortinarius_ there is a wide range of characters varying from species with distinctly sticky caps and stems, some with sticky caps and dry stems to those with both dry caps and stems. A few species are very large and fleshy whilst others are quite slender and many of the latter rapidly change colour on drying out and are then said to be hygrophanous. However, although there is such a large spectrum of characters in a single genus the species all have in common the cortina and rust-coloured gills, the latter often appearing as if powdered with rusty dust.

Utilising the characters mentioned above this very large genus can be split into the following six sections, called by the mycologist subgenera:

a. Large to medium sized fleshy agarics with viscid caps and
stems--_Myxacium_

b. Large, fleshy agarics with viscid or tacky caps when fresh but dry
stems--_Phlegmacium_

c. Large to medium sized agarics with dry, scaly or humid caps and dry
stems which if orange tawny are robust--_Cortinarius_

d. Medium, rarely large, agarics with dry, silky to innately
fibrillose caps, slender stems and frequently with at least part of
the fruit-body yellow, orange or reddish--_Dermocybe_

e. Medium to small agarics with silky fibrillose, non-hygrophanous
caps which may become tacky in wet weather and then usually with
robust, clavate-bulbous stems--_Sericeocybe_

f. Small, less frequently medium or large agarics, all with distinctly
hygrophanous caps--_Hydrocybe_.

In several continental books some or all of these divisions are recognised as distinct genera in their own right. The subgenus _Telamonia_ which occurs in many texts was formerly thought to differ from _Hydrocybe_ in the presence of a universal veil; the universal veil is a second veil which completely envelopes the fruit-body when it is young and is in addition to the cortina. However, the modern treatment would seem to suggest that the presence of the universal veil is not of the utmost importance and so the two subgenera are incorporated into one. The name _Hydrocybe_ reflects the character of changing colour as it dries out because of the loss of water. Within each subgenus the species are distinguished by the colour of the young gills and of the cap, the veil colour and texture, and microscopic characters of the spores, particularly their size.