(i) Fungi of dung and straw heaps
Bolbitius vitellinus (Fries) Fries Yellow cow-pat toadstool
Cap: width 20-40 mm. Stem: width 2-5 mm; length 30-60 mm.
Description:
Cap: chrome-yellow or lemon-yellow when young, paling with age at margin to become cinnamon-buff, bell-shaped but rapidly expanding to become plane or slightly umbonate, smooth, viscid but soon drying; margin striate then radially grooved, often split and the whole cap soon collapsing.
Stem: slender, whitish, cream colour to pale yellow, at apex covered in small, white floccose scales but downy at the base, fragile and soon collapsing.
Gills: adnexed or free, cinnamon-buff, thin and crowded.
Flesh: yellowish, very thin and lacking distinct smell.
Spore print: rust-brown.
Spores: long, yellow-brown under the microscope, ellipsoid with a very distinct germ-pore about 13 × 8 µm in size (11-15 × 6-9 µm).
Facial cystidia: rare, balloon-shaped.
Marginal cystidia: swollen, flask-shaped with a variable, elongate neck.
General Information: This fungus is common on horse droppings or other manures, but it may also be found amongst grass in pastures and in sand-dunes, and gardens on piles of rotting grass stems or straw. It is easily recognised by the colour and rapid expansion of the cap and the sudden collapse of the whole fruit-body. ‘Vitellinus’ means yolk of an egg and refers to the persistently bright yellow cap-centre, so obvious even when the fruit-body collapses. This collapsing is not one of autodigestion as described for members of the genus Coprinus. It is variable both in size and habitat, and I even have records of the fungus growing within herbaceous stems.
Illustrations: LH 153; WD 806.
Stropharia semiglobata (Fries) Quélet Dung-roundhead
Cap: width 10-35 mm. Stem: width 4-7 mm; length 25-50 mm.
Description:
Cap: hemispherical or slightly umbonate, sometimes flattened and hardly expanding even with age, very viscid, smooth, pale yellow-ochre or yellowish tan.
Stem: slender, straight, white then yellowish, smooth, viscid, but then dry and shiny below an imperfectly formed, thin ring.
Gills: adnate, almost triangular in shape, crowded, dark brown to purplish black, but with ochraceous areas at maturity.
Flesh: pale ochre.
Spore-print: purplish brown.
Spores: very long, dark brown under the microscope, smooth, ellipsoid with large germ-pore and about 18 × 10 µm in size (17-20 × 9-10 µm).
Facial cystidia: spindle-shaped, thin-walled and filled with amorphous contents which become yellow in solutions containing ammonia.
Marginal cystidia: spindle-shaped or flask-shaped, numerous, thin-walled and typically yellowing as above.
General Information: ‘Semiglobata’ means hemispherical and refers to the shape of the cap of S. semiglobata; it is a very variable fungus in both size of the cap and the prominence of the ring. The Dung-roundhead grows only on dung which is acidic in its soil status, whilst Panaeolus semiovatus (Fries) Lundell next described ([p. 210]) grows on slightly to distinctly base-rich dung. This may explain why in Britain the Dung-roundhead is the commoner of the two species. However, P. semiovatus was formerly placed in the genus Stropharia because of its blackish spores and distinct ring. The spores of Stropharia in the mass are violaceous black whilst those of P. semiovatus are brownish black. Under the microscope they are also differently coloured and have different chemical compositions as their reaction with dilute solutions of ammonia shows; the spores of the first species turn purplish olive in ammonia and those of the second species become very dark brown.
Illustrations: F 33b; Hvass 171; LH 153; NB 315; WD 753.
Plate 70. Dung-fungi
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Mottle-gills—on dung from Spring until Autumn.
Panaeolus semiovatus (Fries) Lundell
Cap: width 20-70 mm. Stem: width 5-10 mm; length 80-160 mm.
Description:
Cap: oval or bell-shaped, not expanding, dingy whitish or pale clay colour, smooth, slimy when moist, but soon drying and then becoming shiny, often wrinkled and cracked, and ornamented with fragments of veil at the margin.
Stem: dull, straight, rather rigid, tapering upwards, white, and striate at apex above a whitish erect and membranous, often collapsing, ring; yellowish below the ring and whitish and cottony at the slightly swollen base.
Gills: adnate, greyish then black, mottled and crowded.
Flesh: whitish or pale ochre.
Spore-print: black.
Spores: very long, very dark brown under the microscope with large obvious germ-pore and 18 × 10 µm (16-20 × 9-11 µm) in size.
Facial cystidia: flask-shaped and with amorphous contents.
Marginal cystidia: numerous, flask-shaped.
Panaeolus sphinctrinus (Fries) Quélet
Cap: width 15-35 mm. Stem: width 3-6 mm; length 60-95 mm.
Description:
Cap: bell-shaped, hardly expanding, expallent, dark grey to olivaceous black, much paler when dry and zoned when half dry; margin ornamented with a white fringe of veil fragments.
Stem: long, slender, straight, rather rigid but fragile, grey and completely powdered with white.
Gills: adnate, crowded and grey then blackened, mottled throughout except at the white fringed edge.
Flesh: reddish brown.
Spore-print: black.
Spores: long, very dark brown under the microscope, broadly lemon-shaped with large germ-pore, smooth and 14-15 × 9-10 µm in size (14-19 × 8-10 × 10-12 µm).
Facial cystidia: absent.
Marginal cystidia: numerous, cylindrical, flexuous and hyaline.
General Information: P. sphinctrinus is recognised by the overall grey colouration and very distinct white fringe to the cap-margin.
P. campanulatus (Fries) Quélet which is said to be common is in fact infrequent and many records really refer to P. sphinctrinus. The word semiovatus means half ovate and refers to the shape of the cap in P. semiovatus. Sphinctrinus means banded, referring to the zoned cap of the fungus when it is partially dry.
Illustrations: P. semiovatus—LH 145; WD 773. P. sphinctrinus—NB 415; WD 781.
Coprinus cinereus (Fries) S. F. Gray Dung-heap ink-cap
Cap: width 20-40 mm. Stem: width 4-8 mm; length 50-100 mm.
Description:
Cap: oval then rapidly expanding, covered at first in a mass of dense, white or greyish woolly scales which break up into patches and finally leave the cap shiny, brownish grey at centre and striate and dark grey at the margin.
Stem: white, covered particularly towards the base with white, woolly scales, long, fragile, tapering upwards and at the base often elongated into a ‘tap root’ buried in the dung.
Gills: free, white but then rapidly dissolving into a black liquid.
Flesh: thin and whitish.
Spore-print: violaceous black.
Spores: medium sized, ellipsoid, smooth with a distinct germ-pore and 10-12 × 5-6 µm in size.
Facial cystidia: absent.
Marginal cystidia: inflated and large.
General Information: It is found on manure heaps, on straw dung and on silage heaps: very common throughout the year.
C. macrocephalus (Berkeley) Berkeley is very closely related to C. cinereus, but differs in having much larger spores over 12-15 × 7-9 µm, a long cap and a stem which lacks a rooting base.
Coprinus radiatus (Fries) S. F. Gray is smaller in stature and also differs in spore-size (11-14 × 6-7 µm). C. pseudoradiatus Kühner & Josserand is minute and has even smaller spores (7-9 × 4-5 µm). The dung-heap ink-cap has long been used by scientists in genetic studies, usually under the name of C. lagopus (Fries) Fries. However, this latter species, although similar, grows only on woodland detritus; it has narrower spores. The dung-heap ink-cap may be referred to in other books as C. fimetarius Fries or C. macrorhizus (Fries) Rea and whilst cinereus means grey referring to the colour, fimetarius means dung—from the habitat, and macrorhizus refers to the long rooting base found in some specimens.
Illustrations: LH 137; NB 4110; WD 814.
The genus Coprinus—or Ink-caps
The genus Coprinus is easily recognised from all other agarics by the structure and development of the fruit-body. In the field, most species of the genus can be recognised by the gradual conversion of the gills, and often the cap tissue into a black liquid resembling ink—hence the name inky-caps. The conversion of the gills to an inky mass is called autodigestion and the process is complete within a few hours; this mechanism enables spores to be dispersed immediately they have ripened. Unlike other agarics the spores are not shot off into the spaces between the gills, but directly into the air. The gills are parallel-sided in Coprinus and not wedge-shaped as in more normal agarics, and in order to achieve spore dispersal the gills must disintegrate; Coprini are very specialised.
Coprinus is a large genus with over seventy members in the British Isles, many of which are strictly dung-loving. It is impossible to give more than one example in full here, for although many of the large species can be recognised on sight the smaller ones require the aid of a microscope. The interested student must therefore refer to more advanced texts, but in order to demonstrate the diversity of the Coprini and how they are classified the following key to the sections of Coprinus will be found useful.
- 1. Cap naked of any veil fragments, either smooth or covered in minute hairs [2]
- Cap covered when young by powdery or hairy veil, particles of which either may persist on the cap until maturity or may disappear quickly [3]
- 2. Cap completely naked—group Nudi, e.g. C. miser (Karsten) Karsten
- Cap with hairs giving it a frosted appearance—group Setulosi, e.g. C. ephemerus (Fries) Fries, C. pellucidus Karsten and C. bisporus J. Lange
- 3. Veil on the cap composed under the microscope of rounded cells giving the cap a floccose powdery appearance—group Vestiti, e.g. C. patouillardii Quélet, C. niveus (Fries) Fries and C. ephemeroides (Fries) Fries
- Veil on the cap composed under the microscope of elongate cells, either like thin-hairs or strings of sausages [4]
- 4. Veil on the cap composed under the microscope of strings of sausage-shaped cells—group Lanatuli, e.g. C. cinereus, C. pseudoradiatus, C. radiatus (see [p. 211])
- Veil on the cap composed under the microscope of thick- or thin-walled, flexuous or straight, filamentous, hardly inflated cells—group Impexi, e.g. C. filamentifer Kühner, C. vermiculifer Dennis.
Plate 71. Dung-fungi—The genus Coprinus
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General notes on dung-loving fungi and their habitats
Dung fungi are highly satisfactory for demonstrating the diversity and morphology of a group of related organisms within a single ecological system, as representatives of most of the major groups of fungi usually grow on dung after a period of incubation. Dung will always produce characteristic fungi whatever time of year it is collected.
Dung is best incubated in a light place, for example on a window sill, in a warm room on layers of blotting paper or other absorbent material. For rabbit-pellets and samples of similar size petri-dishes are ideal, but for cow, horse and similar types of dung large covered dishes such as casseroles or sandwich containers are very good. Samples should not be kept in airtight containers for long periods of time as under such conditions animal life present rapidly breaks down the dung and induces anaerobic conditions. Instead larvae and earthworms should be excluded from the sample as they decompose the dung and inhibit fungal growth but their activity can be reduced, if causing a problem, by spraying the sample lightly with a proprietary fly-kill aerosol.
By keeping the dung under constant observation during incubation a whole succession of fungi can be seen. Thus the first fungi to appear are the moulds which although numerous need a microscope for their identification. The moulds are followed by a series of Ascomycetes (Sporormia & Sordaria with flask-shaped fruit-bodies and Iodophanus, Coprobia and Cheilymenia with disc-shaped fruit-bodies), which are best sought with the use of a powerful hand-lens or a stereoscopic binocular microscope when their full beauty will be revealed. However, because they need the aid of instruments even to see them they cannot be considered larger fungi. The fruit-bodies of the Basidiomycetes are readily seen with the naked eye, but a hand-lens is still very useful for observing features of the cap and stem, particularly the veil characters. The Basidiomycetes usually conclude the succession of fungi found on dung and soon after this state the dung is colonised by mosses and higher plants and later it is fully incorporated into the soil.
Plate 72. Dung-fungi: Cup fungi and allies
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Dung is a very useful substrate for studying succession. However, equally interesting results can be obtained from observing the fungi which appear on a stump, colonise a newly laid lawn, or indeed those growing on refuse such as a cast-out rug; microscopic and larger fungi are all to be found.
If the dung cannot be incubated immediately it should be dried quickly, for most dung-fungi will survive such treatment and grow when the sample is remoistened. The blotting-paper on which the dung is placed should be kept moist throughout the incubation period.
One large discomycete (up to 80 mm across) occurring on manure-heaps must, however, be mentioned, this is Peziza vesiculosa St Amans (see [p. 200]); the inner surface of this cup-fungus becomes detached from the flesh at maturity and forms blisters.