- Email: [email protected]
Notes on British Chlorophyllum Species
Vol 12 (3)
NOTES ON BRITISH CHLOROPHYLLUM SPECIES Geoffrey Kibby* & Alick Henrici** n Field Mycology 7(4), 2006 Else Vellinga presented the results of her recent studies of the genus Chlorophyllum. This brought to a wider British readership the reasons for transferring what was commonly known as Macrolepiota rachodes (or M. rhacodes, both spellings are in use) into that genus. It also introduced the species C. olivieri and C. brunneum, both now recorded in Britain, and explained their differences. In succeeding years these species have begun to appear on foray records but it has become apparent that many collectors are still uncertain how to distinguish them in the field and under the microscope. In large part this is because there has been a lack of illustrations of the important characters defining the species. In 2009 and 2010 all three species appeared in some abundance in a number of locations in Kew Gardens, Surrey and the opportunity was taken to take photographs of them all. These photographs and notes
on the species are presented here with a key to the British species.
I
Chlorophyllum rachodes (Vittad.) Vellinga Pileus 6–18 cm, cuticle disrupting into broad, often reflexed dark grey-brown scales set against a much paler ground (Fig. 1). Lamellae free, crowded, broad, white to cream. Stipe smooth, distinctly clavate-bulbous but not abruptly so and certainly lacks the often almost volvate appearance of the stipe base of C. brunneum. Annulus thick, complex and with a distinctly double-layered ragged margin (Fig. 2). This should be compared carefully with the much simpler, thinner ring of C. brunneum. All tissues bruise reddish then dark brown with handling. Spores 9–11 x 5.5–7 µm, ellipsoid, with or without a truncate apex, with germ pore (Fig. 8b). Cheilocystidia 10–35 x 8–25 µm, clavate to
Fig. 1. Chlorophyllum rachodes, showing the contrasting cap scales against the almost white ground. Note the double-edged ring and the brown stains from handling. Kew Gardens, Surrey, Sept. 2010. Photo © G. Kibby. *Editorial address **8 Victoria Cottages, Sandycombe Road, Richmond, Surrey TW9 3NW
doi:10.1016/j.fldmyc.2011.06.005
89
Vol 12 (3) spheropedunculate (Fig. 8e). Habitat in deciduous woods, gardens and parks, more rarely in coniferous woods, often in fairy rings. Usually not emerging from deep in the substrate, but loosely anchored near the surface. Notes: In our experience, at least in the southern counties, this is not as common as C. olivieri but commoner than C. brunneum. Most often confused with C. olivieri and best distinguished from that species by the contrasting cap scales, the less deeply rooting stipe, slightly larger spores and smaller cheilocystidia. See Vellinga (2006) p. 139 for a further illustration. Fig. 2. Close-up of the ring of C. rachodes showing the thick, ragged, double-layered margin. Photo © G. Kibby.
Chlorophyllum brunneum (Farl. & Burt) Vellinga Pileus 8–15 cm, usually a rich reddish brown when young, soon disrupting to form large, dark, often reflexed scales on a very pale ground (Fig. 3). Lamellae crowded, free, broad, white to cream. Stipe smooth, with a large, very abrupt basal bulb, sometimes almost volvate and frequently with several stipe bulbs fused together (Fig. 4). Annulus thin, with a dark brown sheathing undersurface (Fig. 5). Spores 9–12(–13) x 6–7.5 µm, ellipsoidamygdaloid, with truncate apex, with germ pore (Fig. 8a).
Cheilocystidia narrowly clavate, 25–50 x 8–20 µm (Fig. 8d). Habitat in parks and gardens, on rich soils or wood chip piles, often in large, dense masses and fairy rings. Notes: Also known as M. rachodes var. bohemica this is a normally rare species in Britain but appeared in large numbers under cedars on woodchip mulch in Kew in 2009–2010. It is also known from a few other localities in the southern counties. The combination of marginate basal bulb and thin, simple ring, brown on the underside make it an easily recognised species. It also
Fig. 3. Chlorophyllum brunneum showing the contrasting cap scales and marginately bulbous base. Note the very young buttons fused at the base and forced downwards, so densely were the fruitbodies packed together. Collected from woodchip mulch, Kew Gardens, Surrey, Oct. 2009. Photograph © G. Kibby.
90
Vol 12 (3)
Fig. 4. Young buttons of C. brunneum with uniform red-brown caps and large marginate bulbs fused together. The ridged margin of the bulb is clearly visible in the cross-section. Photograph © G. Kibby.
Chlorophyllum olivieri (Barla) Vellinga Pileus 5–15 cm, grey-brown to buff brown breaking up into numerous recurved scales set against a similarly coloured ground (Fig. 6). Lamellae crowded, free, white to cream. Stipe smooth, clavate-bulbous but not marginately so. Annulus thick, complex, with ragged double edge (Fig. 7). Spores 8–10(–11) x 5.5–7 µm, ellipsoid, with truncate apex and small germ pore (Fig. 8c). Cheilocystidia clavate to broadly clavate, 35–45 x 15–45 µm (Fig. 8f). Habitat in needle litter of coniferous woods, often deeply buried in the litter, less commonly in deciduous woodlands, gardens etc. Very common in Britain. Notes: The more uniformly coloured cap, complex ring and smaller spores, combined with broadly clavate cheilocystidia help in recognition of this common species. This species has undoubtedly been recorded as C. rachodes in the past until its clear separation by Vellinga and all early records of C. rachodes should be treated with caution without field notes and microscopic examination.
Fig. 5. Close-up of the ring of C. brunneum showing the thin, simple margin and smooth brown underside. Photograph © G. Kibby.
has slightly larger spores and more narrowly clavate cheilocystidia than the other two species. This species was illustrated in Phillips (2006) as C. rhacodes var. bohemica. Note that the characteristic fused clumps of bulbs can also be exhibited by C. rachodes when growing on woodchip mulch although lacking the marginate rim.
91
Vol 12 (3)
Fig. 6. Chlorophyllum olivieri with grey-brown cap scales on a dark greyish ground, double-edged ring and bulbous (but not marginate) stipe base. Photograph © Antony Burnham.
in summer. It resembles C. rachodes but is easily distinguished by its greenish spores which lend a glaucous tint to the lamellae. It is quite toxic and the cause of a number of poisonings where eaten. Macrolepiota venenata Bon We agree with Vellinga that this toxic (and invalidly described) species is most likely a synonym of C. brunneum as described here. Its only clear difference is the supposed lack of clamp connections but these could have been missed in the original material. Most species of Chlorophyllum have been implicated in the past in poisonings, usually involving severe gastric upsets and many people respond adversely to them. All should be treated with caution when being considered as food and they are not recommended here.
Fig. 7. Close-up of the ring of C. olivieri showing the ragged, thick, double edge. Photograph © Antony Burnham.
Chlorophyllum molybdites (G. Mey.) Massee Rarely recorded in Britain this is a tropical species appearing in heated greenhouses for the most part but with increasing summer temperatures it might start to appear in the open. It is a common species growing in fairy rings in parts of northeastern North America for example, where the climate is only a little warmer than our own
92
Vol 12 (3) Key to British species
As with all agarics identification is easier with fresh material, preferably of different ages including young specimens. Spore sizes should be measured, wherever possible, from a spore deposit, to avoid large numbers of immature spores that might be present on the lamellae and which can give an incorrect range of sizes. If you are unable to obtain a spore deposit then mature spores may often be found on the upper surrface of the annulus. Cheilocystidia are best seen on just opened caps, before too many spores have formed. If the material is too old then cheilocystidia frequently collapse back into the lamella edge. Staining with Congo Red will facilitate their examination and measurement.
1. Spores (and lamellae when mature) pale glaucous green ..........................C. molybdites 1. Spores and lamellae pale cream .....................2 2. Base of stipe with large, marginate bulb (reminiscent of Amanita citrina); annulus thin, relatively simple with a smooth brown underside ...................................C. brunneum 2. Base of stipe with a clavate but not marginate bulb; annulus complex, clearly double, pale on the underside...................................................3 3. Cap with uniform grey-brown scales on an only slightly paler grey-brown background; mainly in coniferous woodlands, often deeply rooting in the substrate; spores av. 8.5–10 x 5.8–6.6 µm, cheilocystidia broadly clavate, 35–45 µm across ..............................C. olivieri 3. Cap with contrasting brown scales against a paler, almost white background; more commonly in deciduous woods and gardens, less deeply buried in the substrate; spores av. 9.4–11.2 x 6–7.4 µm, cheilocystidia clavate, 8–25 µm across ...............C. rachodes
Acknowledgements We would like to thank Else Vellinga for constructive comments on a draft of this article.
References Phillips, R. (2006). Mushrooms. Macmillan, London. Vellinga, Else C. (2006). Chlorophyllum in Great Britain. Field Mycology 7(4): 136–140.
Fig. 8. Spores: a) C. brunneum, b) C. rachodes, c) C. olivieri. Scale bars = 10 μm Cheilocystidia: d) C. brunneum, e) C. rachodes, f) C. olivieri. Scale bars = 10 μm.
93
NOTES ON BRITISH CHLOROPHYLLUM SPECIES Geoffrey Kibby* & Alick Henrici** n Field Mycology 7(4), 2006 Else Vellinga presented the results of her recent studies of the genus Chlorophyllum. This brought to a wider British readership the reasons for transferring what was commonly known as Macrolepiota rachodes (or M. rhacodes, both spellings are in use) into that genus. It also introduced the species C. olivieri and C. brunneum, both now recorded in Britain, and explained their differences. In succeeding years these species have begun to appear on foray records but it has become apparent that many collectors are still uncertain how to distinguish them in the field and under the microscope. In large part this is because there has been a lack of illustrations of the important characters defining the species. In 2009 and 2010 all three species appeared in some abundance in a number of locations in Kew Gardens, Surrey and the opportunity was taken to take photographs of them all. These photographs and notes
on the species are presented here with a key to the British species.
I
Chlorophyllum rachodes (Vittad.) Vellinga Pileus 6–18 cm, cuticle disrupting into broad, often reflexed dark grey-brown scales set against a much paler ground (Fig. 1). Lamellae free, crowded, broad, white to cream. Stipe smooth, distinctly clavate-bulbous but not abruptly so and certainly lacks the often almost volvate appearance of the stipe base of C. brunneum. Annulus thick, complex and with a distinctly double-layered ragged margin (Fig. 2). This should be compared carefully with the much simpler, thinner ring of C. brunneum. All tissues bruise reddish then dark brown with handling. Spores 9–11 x 5.5–7 µm, ellipsoid, with or without a truncate apex, with germ pore (Fig. 8b). Cheilocystidia 10–35 x 8–25 µm, clavate to
Fig. 1. Chlorophyllum rachodes, showing the contrasting cap scales against the almost white ground. Note the double-edged ring and the brown stains from handling. Kew Gardens, Surrey, Sept. 2010. Photo © G. Kibby. *Editorial address **8 Victoria Cottages, Sandycombe Road, Richmond, Surrey TW9 3NW
doi:10.1016/j.fldmyc.2011.06.005
89
Vol 12 (3) spheropedunculate (Fig. 8e). Habitat in deciduous woods, gardens and parks, more rarely in coniferous woods, often in fairy rings. Usually not emerging from deep in the substrate, but loosely anchored near the surface. Notes: In our experience, at least in the southern counties, this is not as common as C. olivieri but commoner than C. brunneum. Most often confused with C. olivieri and best distinguished from that species by the contrasting cap scales, the less deeply rooting stipe, slightly larger spores and smaller cheilocystidia. See Vellinga (2006) p. 139 for a further illustration. Fig. 2. Close-up of the ring of C. rachodes showing the thick, ragged, double-layered margin. Photo © G. Kibby.
Chlorophyllum brunneum (Farl. & Burt) Vellinga Pileus 8–15 cm, usually a rich reddish brown when young, soon disrupting to form large, dark, often reflexed scales on a very pale ground (Fig. 3). Lamellae crowded, free, broad, white to cream. Stipe smooth, with a large, very abrupt basal bulb, sometimes almost volvate and frequently with several stipe bulbs fused together (Fig. 4). Annulus thin, with a dark brown sheathing undersurface (Fig. 5). Spores 9–12(–13) x 6–7.5 µm, ellipsoidamygdaloid, with truncate apex, with germ pore (Fig. 8a).
Cheilocystidia narrowly clavate, 25–50 x 8–20 µm (Fig. 8d). Habitat in parks and gardens, on rich soils or wood chip piles, often in large, dense masses and fairy rings. Notes: Also known as M. rachodes var. bohemica this is a normally rare species in Britain but appeared in large numbers under cedars on woodchip mulch in Kew in 2009–2010. It is also known from a few other localities in the southern counties. The combination of marginate basal bulb and thin, simple ring, brown on the underside make it an easily recognised species. It also
Fig. 3. Chlorophyllum brunneum showing the contrasting cap scales and marginately bulbous base. Note the very young buttons fused at the base and forced downwards, so densely were the fruitbodies packed together. Collected from woodchip mulch, Kew Gardens, Surrey, Oct. 2009. Photograph © G. Kibby.
90
Vol 12 (3)
Fig. 4. Young buttons of C. brunneum with uniform red-brown caps and large marginate bulbs fused together. The ridged margin of the bulb is clearly visible in the cross-section. Photograph © G. Kibby.
Chlorophyllum olivieri (Barla) Vellinga Pileus 5–15 cm, grey-brown to buff brown breaking up into numerous recurved scales set against a similarly coloured ground (Fig. 6). Lamellae crowded, free, white to cream. Stipe smooth, clavate-bulbous but not marginately so. Annulus thick, complex, with ragged double edge (Fig. 7). Spores 8–10(–11) x 5.5–7 µm, ellipsoid, with truncate apex and small germ pore (Fig. 8c). Cheilocystidia clavate to broadly clavate, 35–45 x 15–45 µm (Fig. 8f). Habitat in needle litter of coniferous woods, often deeply buried in the litter, less commonly in deciduous woodlands, gardens etc. Very common in Britain. Notes: The more uniformly coloured cap, complex ring and smaller spores, combined with broadly clavate cheilocystidia help in recognition of this common species. This species has undoubtedly been recorded as C. rachodes in the past until its clear separation by Vellinga and all early records of C. rachodes should be treated with caution without field notes and microscopic examination.
Fig. 5. Close-up of the ring of C. brunneum showing the thin, simple margin and smooth brown underside. Photograph © G. Kibby.
has slightly larger spores and more narrowly clavate cheilocystidia than the other two species. This species was illustrated in Phillips (2006) as C. rhacodes var. bohemica. Note that the characteristic fused clumps of bulbs can also be exhibited by C. rachodes when growing on woodchip mulch although lacking the marginate rim.
91
Vol 12 (3)
Fig. 6. Chlorophyllum olivieri with grey-brown cap scales on a dark greyish ground, double-edged ring and bulbous (but not marginate) stipe base. Photograph © Antony Burnham.
in summer. It resembles C. rachodes but is easily distinguished by its greenish spores which lend a glaucous tint to the lamellae. It is quite toxic and the cause of a number of poisonings where eaten. Macrolepiota venenata Bon We agree with Vellinga that this toxic (and invalidly described) species is most likely a synonym of C. brunneum as described here. Its only clear difference is the supposed lack of clamp connections but these could have been missed in the original material. Most species of Chlorophyllum have been implicated in the past in poisonings, usually involving severe gastric upsets and many people respond adversely to them. All should be treated with caution when being considered as food and they are not recommended here.
Fig. 7. Close-up of the ring of C. olivieri showing the ragged, thick, double edge. Photograph © Antony Burnham.
Chlorophyllum molybdites (G. Mey.) Massee Rarely recorded in Britain this is a tropical species appearing in heated greenhouses for the most part but with increasing summer temperatures it might start to appear in the open. It is a common species growing in fairy rings in parts of northeastern North America for example, where the climate is only a little warmer than our own
92
Vol 12 (3) Key to British species
As with all agarics identification is easier with fresh material, preferably of different ages including young specimens. Spore sizes should be measured, wherever possible, from a spore deposit, to avoid large numbers of immature spores that might be present on the lamellae and which can give an incorrect range of sizes. If you are unable to obtain a spore deposit then mature spores may often be found on the upper surrface of the annulus. Cheilocystidia are best seen on just opened caps, before too many spores have formed. If the material is too old then cheilocystidia frequently collapse back into the lamella edge. Staining with Congo Red will facilitate their examination and measurement.
1. Spores (and lamellae when mature) pale glaucous green ..........................C. molybdites 1. Spores and lamellae pale cream .....................2 2. Base of stipe with large, marginate bulb (reminiscent of Amanita citrina); annulus thin, relatively simple with a smooth brown underside ...................................C. brunneum 2. Base of stipe with a clavate but not marginate bulb; annulus complex, clearly double, pale on the underside...................................................3 3. Cap with uniform grey-brown scales on an only slightly paler grey-brown background; mainly in coniferous woodlands, often deeply rooting in the substrate; spores av. 8.5–10 x 5.8–6.6 µm, cheilocystidia broadly clavate, 35–45 µm across ..............................C. olivieri 3. Cap with contrasting brown scales against a paler, almost white background; more commonly in deciduous woods and gardens, less deeply buried in the substrate; spores av. 9.4–11.2 x 6–7.4 µm, cheilocystidia clavate, 8–25 µm across ...............C. rachodes
Acknowledgements We would like to thank Else Vellinga for constructive comments on a draft of this article.
References Phillips, R. (2006). Mushrooms. Macmillan, London. Vellinga, Else C. (2006). Chlorophyllum in Great Britain. Field Mycology 7(4): 136–140.
Fig. 8. Spores: a) C. brunneum, b) C. rachodes, c) C. olivieri. Scale bars = 10 μm Cheilocystidia: d) C. brunneum, e) C. rachodes, f) C. olivieri. Scale bars = 10 μm.
93