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Agarics and Boletes of Alder Carr
Vol 11 (1) AGARICS AND BOLETES OF ALDER CARR Geoffrey Kibby
stipe, and very commonly with prominent cheilocystidia, these usually small and rather nondescript agarics are surprisingly difficult to identify. Naucorias need careful interpretation of subtle field characteristics, combined with the usual examination of microscopical characters. They may appear in large drifts and frequently several species may grow in close proximity and mixed collections are common, adding to the difficulties of identification. The result is a number of often complex synonymies and records of this genus must be treated with caution if unaccompanied by a full and precise description. We have around 16 species in Britain of which the commonest is undoubtedly the pale yellowish N. escharioides (Fig. 1), followed by N. striatula, a reddish-brown species with a very pellucidstriate cap when moist. The remainder are of varying degrees of scarcity. Rather better defined are a small number of species of Cortinarius—usually an extremely difficult group to identify. Most easily recognised is C. lilacinopusillus (Fig. 2) (= C. bibulus sensu auct.), a beautiful species up to about 1 cm across the cap with pale lilac to darker violet colours overall and spores 9–10 x
ur native alder—Alnus glutinosa—has a number of associated mycorrhizal agarics which occur with no other host; some common, some rarely seen. However, because alders rarely grow in pure stands one can also expect to find common birch and willow associates nearby, since these trees are also commonly found in the damp or wet areas that alders prefer. This must be allowed for when attempting to identify agarics found in alder carrs. At times alder carrs produce agarics in huge numbers, often after there has been a wet period and the woods have flooded and then subsequently drained, the fruitbodies frequently appearing right at the retreating water’s edge. Pre-eminent among the agarics of alders is the genus Naucoria, also widely known as Alnicola (see Henrici, 2008 for a discussion of this issue plus a key to species in Britain). Distinguished by brown, often warted spores, variable amounts of veil on cap margin and
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Fig. 1. Naucoria escharioides is often prolific in alder carrs, recognised by its pale, yellowish cap and delicately fibrillose stipe. The Wrekin, Shropshire, October 2009. Photo © G.Kibby
doi:10.1016/j.fldmyc.2010.01.006
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Vol 11 (1)
Fig. 2. Cortinarius lilacinopusillus is distinguished by its entirely violet to lilac fruitbodies and small size (approx. 1 cm across). Flitwick Moor, Bedfordshire, Sept. 2009. Photo © Antony Burnham.
5–6.5 µm. Also violet but darker, almost black at centre and with slightly smaller spores (7.5–8.5 x 4.5–5.5 µm) is C. americanus which is not authentically British but might occur here. British material of C. lilacinopusillus should be carefully examined to check for this potential look-alike. A photograph of what is regarded as C. americanus may be found in Breitenbach & Kränzlin (2000) as C. bibulus. Larger, to almost 4 cm, but almost entirely black to dark grey-brown with silky grey-white veil and with tan-brown gills is C. alnetorum. Its stipe may be slightly violet at the apex and it has spores 8.5–10.5 x 5–5.5 µm. This is one of the more frequent species of Cortinarius in alder swamps although surprisingly difficult to spot due to its dark colouration. Even darker and without any violet tones whatever is the much rarer C. atropusillus (Fig. 3). This species was described by Moser and is stated to grow with Alnus viridis (a planted tree in this country). It differs from C. alnetorum by its colour, its much reduced veil and by its smaller spores (7.5–9.5 x 4.5–5.5 (6) µm). The collection illustrated agrees with this description and was made in the extensive alder carrs surrounding Colemere Lake in N. Shropshire. It should be noted, however, that the alders here are the
native A. glutinosa, not A. viridis. It seems unlikely to me, however, that the fungus would be restricted to just one species of Alnus and all other characters agree well with the original description.
Fig. 3. Cortinarius atropusillus, Colemere, N. Shropshire, 2008. Photo © Geoffrey Kibby.
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Fig. 4. A typical alder carr at Hurst Wood, Kent showing the often dense understorey which can make hunting agarics rathe e top right: Russula alnetorum, Rowley Woods, Bucks. © Martyn Ainsworth; Centre: Laccaria purpureobadia, Flitwick Mo o Geoffrey Kibby; bottom right: Gyrodon lividus, Petts Wood, Kent © Jo Weightman.
e er difficult. Species inset are: top left: Cortinarius helvelloides, Flitwick Moor, Bedfordshire, Sept. 2009 © Antony Burnham; o oor, Bedfordshire, Sept. 2009 © Antony Burnham; bottom left: Amanita friabilis, Ercall Quarry, Shropshire, Oct. 2009 ©
Vol 11 (1) Another small Cortinarius species, but one with more tawny yellow colours is C. helvelloides (see Fig. 4, centre spread, top left). This species may grow in large numbers under alder but has also been recorded more rarely growing with willows. It is easily recognised when fresh by its bright tawny yellow-brown cap and stipe, golden yellow veil and violaceous gills and stipe apex when young. The cap can be quite scaly-fibrillose from the golden veil. Although normally about a centimetre across it will occasionally reach 3–4 cm. Its spores are broadly ellipsoid, 8–10 x 5–6.5 µm and distinctly warted. While not exclusively with alder—it also grows with Salix and Betula—Laccaria purpureobadia is certainly commonly found under this host. When fresh the colours are very striking (Fig. 4, centre spread in middle), a deep vinaceous-pink to purplish-red, especially the stipe. With age it can fade and appear very similar to other Laccaria species which may also grow in the same habitat. Microscopically it is distinguished by its broadly ellipsoid spores, 8.5–10 x 7–8 µm with spines up to 1 µm. It appears to be genuinely rare in Britain although widely distributed. The genus Amanita has only one species in this country associated with alder and it is an exceedingly rare one—A. friabilis (see Fig. 4, centre spread, bottom left). The smallest of our Amanita species, it is recognised by its greybrown cap, 3–5 cm across, frequently covered with very friable greyish-white veil which is composed of numerous sphaerocysts— rounded, balloon-like cells. The stipe is white with a slightly woolly-floccose surface and the volva is very small and easily broken up in the soil. Its spores are slightly ellipsoid, 10–12.5 x 8–10 µm. The specimen illustrated was found under a solitary alder on relatively dry soil at the side of a quarry in Shropshire but it will also grow in typical wet alder carrs. The Boletales are represented by one typical bolete, Gyrodon lividus and one agaricoid member, Paxillus rubicundulus, both excusively with alder and both placed in the family Paxillaceae. Gyrodon lividus (Fig. 4, centre spread bottom right) is a rare species found mainly in the southern counties of England but even there with a very patchy
distribution. It is quite unmistakable with its deeply decurrent bright yellow tubes which bruise deep blue on the slightest handling. From the top however it can look very similar to a Paxillus; so all supposed Paxillus fruitbodies should be given a second and closer look just in case! Gyrodon is also distinguished by its rather small, pale brown ellipsoid spores. Paxillus rubicundulus (Fig. 5, top left) is not uncommon in stands of alder and although having a very similar appearance to P. involutus, which also commonly grows in mixed alder/birch woodlands, it differs in its more adpressed-scaly cap surface and distinctly smaller spores (5.5–8.5 x 4–5 µm versus 7–11 x 5–6.5 µm in P. involutus). If Salix species are present, especially S. cinerea then specimens should be tested with ammonia. There is a another taxon – possibly undescribed – so far only found with S. cinerea, whose cap cuticle turns bright green with ammonia (Fig. 5, bottom right) and which differs in its brighter colours, larger spores, and possibly other micro-characters. We are currently trying to ascertain if this taxon is known and/or described elsewhere and whether it was included as part of the molecular work undertaken in recent studies on this genus. The Family Russulaceae is represented under alder by one Russula species and several Lactarius species. Russula alnetorum (centre spread, top right) is not uncommon and seems tolerant of a wide variation in moisture levels; I have found it just inches from open water but also in quite dry alder woods. The small (3-5 cm) cap varies from deep purple to brownish-violet and the white, often grooved, stipe rapidly discolours to grey or brownish when wet and this is the best field character. The gills and flesh taste weakly to moderately acrid. Its spores have a well developed reticulum and it has 0–1 septate pileocystidia on the cap cuticle. It might be confused with R. fragilis but that has an unchanging stipe, 1–2 septate pileocystidia and a much hotter taste. There are four species of Lactarius in Britain associated exclusively with alder of which the largest and perhaps most distinctive is L. lilacinus (Fig. 6). A beautiful pale vinaceous-pink, pale brick or even rose-pink in colour the cap surface is finely velutinous to
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Fig. 5.Top left, three fruitbodies of Paxillus rubicundulus, mycorrhizal with Alnus; botttom right, three fruitbodies of a Paxillus species associated with Salix, showing the vivid green stain produced following application of ammonia. Photograph © Geoffrey Kibby.
Fig. 6. Lactarius lilacinus under alders at the edge of Colemere Lake, Shropshire, October 19, 2009. Photograph © Geoffrey Kibby.
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Vol 11 (1) minutely squamulose. The milk is rather sparse, white and slightly bitter to moderately acrid. It seems to like growing very close to open water and in the photo shown the water was just a few inches to the right of the specimens. It might be mistaken for L. spinosulus , which can also occur with Alnus though more usually with Betula. It has similar colours but has a more strongly zonate and much more hispid-scaly cap and strongly zebroid ridges on the spores. There is a trio of small to very small species under alder which are rather difficult to separate in the field: L. obscuratus, L. omphaliformis and L. cyathuliformis. All are of about equal frequency and must be examined carefully both macro- and microscopically to determine their identity. L. omphaliformis is perhaps the easiest to distinguish since its rather brightly coloured, orange-brown cap soon becomes cracked and minutely scaly, rather like a Laccaria species. It has a preference for deep moss carpets, typically of Sphagnum species. Its spores are 7–9.5 x 5.5–7.8 µm. L. cyathuliformis (Fig. 7) can often be identified in the field by the distinctly olivaceous tones of its cap. This is particularly apparent when a number of fruitbodies are
Fig. 7. Lactarius cyathuliformis showing the distinct olivaceous central spot on the cap. Oldhouse Wood, Bucks. 8 Sept. 2009. Photo © Martyn Ainsworth.
gathered together and assessed as a group. They will usually have a darker, olivaceous central spot. It also has the largest spores of the group: 7–11 x 6–8.5 µm. L. obscuratus (Fig. 8) is usually smaller than L. cyathuliformis and more gracile, with brighter, more orange-brown or buff colours and with a less obvious olivaceous component. Again, this is easier to appreciate when a collection of both species is available. Its spores are the smallest in the group: 6.3–9 x 5–7 µm. For a fuller discussion of this difficult group and the problems associated with their identification see Heilmann-Clausen et al. (1998).
References Breitenbach, J. & Kränzlin, F. (2000). Fungi of Switzerland, Vol. 5. Mykologia Luzern. Heilmann-Clausen, J., Verbeken, A. & Vesterholt, J. (1998). The Genus Lactarius. Fungi of Northern Europe, Vol. 2. Henrici, A. (2008). Keys to Naucoria in Britain. Field Mycology 9(2): 55–62.
Fig. 8. Lactarius obscuratus with more orange-brown colours. Rowley Woods, Bucks. 26 Aug. 2009. Photo © Martyn Ainsworth.
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stipe, and very commonly with prominent cheilocystidia, these usually small and rather nondescript agarics are surprisingly difficult to identify. Naucorias need careful interpretation of subtle field characteristics, combined with the usual examination of microscopical characters. They may appear in large drifts and frequently several species may grow in close proximity and mixed collections are common, adding to the difficulties of identification. The result is a number of often complex synonymies and records of this genus must be treated with caution if unaccompanied by a full and precise description. We have around 16 species in Britain of which the commonest is undoubtedly the pale yellowish N. escharioides (Fig. 1), followed by N. striatula, a reddish-brown species with a very pellucidstriate cap when moist. The remainder are of varying degrees of scarcity. Rather better defined are a small number of species of Cortinarius—usually an extremely difficult group to identify. Most easily recognised is C. lilacinopusillus (Fig. 2) (= C. bibulus sensu auct.), a beautiful species up to about 1 cm across the cap with pale lilac to darker violet colours overall and spores 9–10 x
ur native alder—Alnus glutinosa—has a number of associated mycorrhizal agarics which occur with no other host; some common, some rarely seen. However, because alders rarely grow in pure stands one can also expect to find common birch and willow associates nearby, since these trees are also commonly found in the damp or wet areas that alders prefer. This must be allowed for when attempting to identify agarics found in alder carrs. At times alder carrs produce agarics in huge numbers, often after there has been a wet period and the woods have flooded and then subsequently drained, the fruitbodies frequently appearing right at the retreating water’s edge. Pre-eminent among the agarics of alders is the genus Naucoria, also widely known as Alnicola (see Henrici, 2008 for a discussion of this issue plus a key to species in Britain). Distinguished by brown, often warted spores, variable amounts of veil on cap margin and
O
Fig. 1. Naucoria escharioides is often prolific in alder carrs, recognised by its pale, yellowish cap and delicately fibrillose stipe. The Wrekin, Shropshire, October 2009. Photo © G.Kibby
doi:10.1016/j.fldmyc.2010.01.006
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Vol 11 (1)
Fig. 2. Cortinarius lilacinopusillus is distinguished by its entirely violet to lilac fruitbodies and small size (approx. 1 cm across). Flitwick Moor, Bedfordshire, Sept. 2009. Photo © Antony Burnham.
5–6.5 µm. Also violet but darker, almost black at centre and with slightly smaller spores (7.5–8.5 x 4.5–5.5 µm) is C. americanus which is not authentically British but might occur here. British material of C. lilacinopusillus should be carefully examined to check for this potential look-alike. A photograph of what is regarded as C. americanus may be found in Breitenbach & Kränzlin (2000) as C. bibulus. Larger, to almost 4 cm, but almost entirely black to dark grey-brown with silky grey-white veil and with tan-brown gills is C. alnetorum. Its stipe may be slightly violet at the apex and it has spores 8.5–10.5 x 5–5.5 µm. This is one of the more frequent species of Cortinarius in alder swamps although surprisingly difficult to spot due to its dark colouration. Even darker and without any violet tones whatever is the much rarer C. atropusillus (Fig. 3). This species was described by Moser and is stated to grow with Alnus viridis (a planted tree in this country). It differs from C. alnetorum by its colour, its much reduced veil and by its smaller spores (7.5–9.5 x 4.5–5.5 (6) µm). The collection illustrated agrees with this description and was made in the extensive alder carrs surrounding Colemere Lake in N. Shropshire. It should be noted, however, that the alders here are the
native A. glutinosa, not A. viridis. It seems unlikely to me, however, that the fungus would be restricted to just one species of Alnus and all other characters agree well with the original description.
Fig. 3. Cortinarius atropusillus, Colemere, N. Shropshire, 2008. Photo © Geoffrey Kibby.
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Fig. 4. A typical alder carr at Hurst Wood, Kent showing the often dense understorey which can make hunting agarics rathe e top right: Russula alnetorum, Rowley Woods, Bucks. © Martyn Ainsworth; Centre: Laccaria purpureobadia, Flitwick Mo o Geoffrey Kibby; bottom right: Gyrodon lividus, Petts Wood, Kent © Jo Weightman.
e er difficult. Species inset are: top left: Cortinarius helvelloides, Flitwick Moor, Bedfordshire, Sept. 2009 © Antony Burnham; o oor, Bedfordshire, Sept. 2009 © Antony Burnham; bottom left: Amanita friabilis, Ercall Quarry, Shropshire, Oct. 2009 ©
Vol 11 (1) Another small Cortinarius species, but one with more tawny yellow colours is C. helvelloides (see Fig. 4, centre spread, top left). This species may grow in large numbers under alder but has also been recorded more rarely growing with willows. It is easily recognised when fresh by its bright tawny yellow-brown cap and stipe, golden yellow veil and violaceous gills and stipe apex when young. The cap can be quite scaly-fibrillose from the golden veil. Although normally about a centimetre across it will occasionally reach 3–4 cm. Its spores are broadly ellipsoid, 8–10 x 5–6.5 µm and distinctly warted. While not exclusively with alder—it also grows with Salix and Betula—Laccaria purpureobadia is certainly commonly found under this host. When fresh the colours are very striking (Fig. 4, centre spread in middle), a deep vinaceous-pink to purplish-red, especially the stipe. With age it can fade and appear very similar to other Laccaria species which may also grow in the same habitat. Microscopically it is distinguished by its broadly ellipsoid spores, 8.5–10 x 7–8 µm with spines up to 1 µm. It appears to be genuinely rare in Britain although widely distributed. The genus Amanita has only one species in this country associated with alder and it is an exceedingly rare one—A. friabilis (see Fig. 4, centre spread, bottom left). The smallest of our Amanita species, it is recognised by its greybrown cap, 3–5 cm across, frequently covered with very friable greyish-white veil which is composed of numerous sphaerocysts— rounded, balloon-like cells. The stipe is white with a slightly woolly-floccose surface and the volva is very small and easily broken up in the soil. Its spores are slightly ellipsoid, 10–12.5 x 8–10 µm. The specimen illustrated was found under a solitary alder on relatively dry soil at the side of a quarry in Shropshire but it will also grow in typical wet alder carrs. The Boletales are represented by one typical bolete, Gyrodon lividus and one agaricoid member, Paxillus rubicundulus, both excusively with alder and both placed in the family Paxillaceae. Gyrodon lividus (Fig. 4, centre spread bottom right) is a rare species found mainly in the southern counties of England but even there with a very patchy
distribution. It is quite unmistakable with its deeply decurrent bright yellow tubes which bruise deep blue on the slightest handling. From the top however it can look very similar to a Paxillus; so all supposed Paxillus fruitbodies should be given a second and closer look just in case! Gyrodon is also distinguished by its rather small, pale brown ellipsoid spores. Paxillus rubicundulus (Fig. 5, top left) is not uncommon in stands of alder and although having a very similar appearance to P. involutus, which also commonly grows in mixed alder/birch woodlands, it differs in its more adpressed-scaly cap surface and distinctly smaller spores (5.5–8.5 x 4–5 µm versus 7–11 x 5–6.5 µm in P. involutus). If Salix species are present, especially S. cinerea then specimens should be tested with ammonia. There is a another taxon – possibly undescribed – so far only found with S. cinerea, whose cap cuticle turns bright green with ammonia (Fig. 5, bottom right) and which differs in its brighter colours, larger spores, and possibly other micro-characters. We are currently trying to ascertain if this taxon is known and/or described elsewhere and whether it was included as part of the molecular work undertaken in recent studies on this genus. The Family Russulaceae is represented under alder by one Russula species and several Lactarius species. Russula alnetorum (centre spread, top right) is not uncommon and seems tolerant of a wide variation in moisture levels; I have found it just inches from open water but also in quite dry alder woods. The small (3-5 cm) cap varies from deep purple to brownish-violet and the white, often grooved, stipe rapidly discolours to grey or brownish when wet and this is the best field character. The gills and flesh taste weakly to moderately acrid. Its spores have a well developed reticulum and it has 0–1 septate pileocystidia on the cap cuticle. It might be confused with R. fragilis but that has an unchanging stipe, 1–2 septate pileocystidia and a much hotter taste. There are four species of Lactarius in Britain associated exclusively with alder of which the largest and perhaps most distinctive is L. lilacinus (Fig. 6). A beautiful pale vinaceous-pink, pale brick or even rose-pink in colour the cap surface is finely velutinous to
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Fig. 5.Top left, three fruitbodies of Paxillus rubicundulus, mycorrhizal with Alnus; botttom right, three fruitbodies of a Paxillus species associated with Salix, showing the vivid green stain produced following application of ammonia. Photograph © Geoffrey Kibby.
Fig. 6. Lactarius lilacinus under alders at the edge of Colemere Lake, Shropshire, October 19, 2009. Photograph © Geoffrey Kibby.
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Vol 11 (1) minutely squamulose. The milk is rather sparse, white and slightly bitter to moderately acrid. It seems to like growing very close to open water and in the photo shown the water was just a few inches to the right of the specimens. It might be mistaken for L. spinosulus , which can also occur with Alnus though more usually with Betula. It has similar colours but has a more strongly zonate and much more hispid-scaly cap and strongly zebroid ridges on the spores. There is a trio of small to very small species under alder which are rather difficult to separate in the field: L. obscuratus, L. omphaliformis and L. cyathuliformis. All are of about equal frequency and must be examined carefully both macro- and microscopically to determine their identity. L. omphaliformis is perhaps the easiest to distinguish since its rather brightly coloured, orange-brown cap soon becomes cracked and minutely scaly, rather like a Laccaria species. It has a preference for deep moss carpets, typically of Sphagnum species. Its spores are 7–9.5 x 5.5–7.8 µm. L. cyathuliformis (Fig. 7) can often be identified in the field by the distinctly olivaceous tones of its cap. This is particularly apparent when a number of fruitbodies are
Fig. 7. Lactarius cyathuliformis showing the distinct olivaceous central spot on the cap. Oldhouse Wood, Bucks. 8 Sept. 2009. Photo © Martyn Ainsworth.
gathered together and assessed as a group. They will usually have a darker, olivaceous central spot. It also has the largest spores of the group: 7–11 x 6–8.5 µm. L. obscuratus (Fig. 8) is usually smaller than L. cyathuliformis and more gracile, with brighter, more orange-brown or buff colours and with a less obvious olivaceous component. Again, this is easier to appreciate when a collection of both species is available. Its spores are the smallest in the group: 6.3–9 x 5–7 µm. For a fuller discussion of this difficult group and the problems associated with their identification see Heilmann-Clausen et al. (1998).
References Breitenbach, J. & Kränzlin, F. (2000). Fungi of Switzerland, Vol. 5. Mykologia Luzern. Heilmann-Clausen, J., Verbeken, A. & Vesterholt, J. (1998). The Genus Lactarius. Fungi of Northern Europe, Vol. 2. Henrici, A. (2008). Keys to Naucoria in Britain. Field Mycology 9(2): 55–62.
Fig. 8. Lactarius obscuratus with more orange-brown colours. Rowley Woods, Bucks. 26 Aug. 2009. Photo © Martyn Ainsworth.
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