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Phellinus tremulae, a new British record on aspens in Scotland
Volume 15, Part 3, August 2001
Phellinus tremulae, a new British Record on Aspens in Scotland ERNEST E. EMMETT & VALERIE E. EMMETT Drumlins, Newtonmore Road, Kingussie, In verness-shire PH21 IHD
Phellinus tremulae (Bond.) Bond. & Borisov is described as a newly recorded species (NBR 190) from Great Britain. It has been found by the authors to be common in stands of Aspen (Populus tremula) in the Spey Valley, Invernessshire, Scotland; and was first found at Insh Marshes RSPB Reserve in March 2000. The basidiocarps are perennial and very variable in shape and size; they are firmly attached to the tree bole or branch . The y may be small to medium sized wedge-shaped brackets, 20 - 100 mm wide, projecting from the tr ee bole up to approximately 50 mm , or irregularly shaped forms extending along the underside of dead branches from the junction of the branch with the tree bole. Small specimens are easily overlooked. The basidiocarps are wood hard , with both the crust and th e hymenium forming an obtuse angle with the tr ee bole, giving a triangular cross-sectional shape. Some of the basidiocarps on the boles of
Fig 1 Basidi ocarp of Phellinus tremulae, with outgrowths on hymenium, taken in December at Insh RSPB Reserve, Invernessshire.
Fig 2 Actively growing hymenium showing the richer colour. Basidiocarps are sometimes odd shapes; this example shows th e radial cracking and the bicoloured edge, taken in January at Tarrig Mhore, near Grantown on Spey.
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Volume 15, Part 3, August 2001 trees, grow by the hymenium extending downwards, with smaller folding projections developing on the surface of the hymenium (Fig 1). The upper side is very hard, dark grey, showing distinct annual zones, and with a pattern of radial or vertical cracks; older specimens are often greenish with algae and some become encrusted with lichens. The margin or boundary is sharply defined as a band of sterile tissue 4 to 6 mm wide separating the pores from the crust. In actively growing basidiocarps, it is the same colour as the pore surface, which is some shade of dark brown with a fine velvety texture. With weathering, it becomes pale and may appear bicoloured during this transition. The surface of the hymenium is smooth, planar, convex, occasionally concave. In young and dormant specimens, it is pale buff to dull brown darkening with age, but active spore-producing pores have a richer colour (Fig 2). The pores are almost circular, 100[lm in diameter and 5-6 to the mm; the dissepiment edges are woolly fibrous, slightly dentate under the microscope, and they vary in thickness from 100to 200 urn in the main part of the hymenium. The inside of old pores is stuffed with white mycelium. If a section is taken through the basidiocarp, it will be seen that the pores of the current year are clear but those of earlier years are stuffed with hyphae. The spores are colourless, non-amyloid, and acyanophilic, 4-5 x 2-6 [lm. The hymenial setae are rather simple, thick-walled short and sharply pointed, 20-30 [lm long. The hyphal system is dimitic, the generative hyphae without clamps, a feature of the genus. The skeletal hyphae are reported to be parallel in the trama of the hymenium. The authors have found this to be difficult to observe. The required thin section is difficult to obtain without a microtome. However, the feature can be observed with a good quality stereoscopic microscope, using incident light on an exposed portion of hymenium cut parallel to the pore axis. The only other species in the genus with parallel tramal hyphae is P laevigatus, which is a resupinate species associated with birch (Betula spp.) and differing in other significant respects from P tremulae.
Phellinus tremulae is a serIOUS parasite of Aspen, where it causes white rot. It is well known in Fennoscandia, and also occurs in Northern Europe, Northern Asia and North America where Aspen is a common component of the northern temperate and boreal forests. It is also reported to parasitise White Poplar (P alba) and Grey Poplar (P x canescens) in Fennoscandia, but so far the authors have only found it on P tremula and not on other poplar species in Badenoch & Strathspey. In Fennoscandia it is mostly known from large old trees, with basidiocarps occurring from 2 to 10 metres above the ground. The authors have found that the fungus is not confined to old and large specimens of P tremula. Measurements of 54 infected trees in woodlands of Badenoch and Strathspey show it to be present on apparently young trees as small as 65 em circumference at breast height. The basidiocarps have been found as low as 60 em above the ground, much lower than reported for trees in Fennoscandia. They are found on standing and fallen trees and the fungus is reported to continue to grow for some years on dead trees. Attached dead branches and rot holes are reported to act as channels for infection of the living tree with basidiocarp formation close to a scar or snag. This is not always obvious, in the trees seen by the authors some arise directly from apparently undamaged areas of the tree boles. A sample provided for the Royal Botanic Gardens, Kew is in culture and the culture has the sweet smell of Oil of Wintergreen, noted by Niemala (1974). The authors wish to thank Prof. L. Ryvarden (Oslo), for his confirmation of the identification of the fungus, Dr. E. M. Saunders (RBG Kew) for successfully getting the species into culture, Dr. T. Niemala for helpful comments and copies of his papers, Mr A. Henrici for drawing Niemala's paper to our attention, and the RSPB for their cooperation. References Niemala, T. (1974) On Fennoscandian Polypores. III Phellinus tremulae (Bond.) Bond. & Borisov Ann. Bot. Fennici 11: 202-215. Ryvarden 1. & Gilbertson R. 1. (1994) European Polypores, Part 2; Fungiflora, Oslo.
Phellinus tremulae, a new British Record on Aspens in Scotland ERNEST E. EMMETT & VALERIE E. EMMETT Drumlins, Newtonmore Road, Kingussie, In verness-shire PH21 IHD
Phellinus tremulae (Bond.) Bond. & Borisov is described as a newly recorded species (NBR 190) from Great Britain. It has been found by the authors to be common in stands of Aspen (Populus tremula) in the Spey Valley, Invernessshire, Scotland; and was first found at Insh Marshes RSPB Reserve in March 2000. The basidiocarps are perennial and very variable in shape and size; they are firmly attached to the tree bole or branch . The y may be small to medium sized wedge-shaped brackets, 20 - 100 mm wide, projecting from the tr ee bole up to approximately 50 mm , or irregularly shaped forms extending along the underside of dead branches from the junction of the branch with the tree bole. Small specimens are easily overlooked. The basidiocarps are wood hard , with both the crust and th e hymenium forming an obtuse angle with the tr ee bole, giving a triangular cross-sectional shape. Some of the basidiocarps on the boles of
Fig 1 Basidi ocarp of Phellinus tremulae, with outgrowths on hymenium, taken in December at Insh RSPB Reserve, Invernessshire.
Fig 2 Actively growing hymenium showing the richer colour. Basidiocarps are sometimes odd shapes; this example shows th e radial cracking and the bicoloured edge, taken in January at Tarrig Mhore, near Grantown on Spey.
•
•
Volume 15, Part 3, August 2001 trees, grow by the hymenium extending downwards, with smaller folding projections developing on the surface of the hymenium (Fig 1). The upper side is very hard, dark grey, showing distinct annual zones, and with a pattern of radial or vertical cracks; older specimens are often greenish with algae and some become encrusted with lichens. The margin or boundary is sharply defined as a band of sterile tissue 4 to 6 mm wide separating the pores from the crust. In actively growing basidiocarps, it is the same colour as the pore surface, which is some shade of dark brown with a fine velvety texture. With weathering, it becomes pale and may appear bicoloured during this transition. The surface of the hymenium is smooth, planar, convex, occasionally concave. In young and dormant specimens, it is pale buff to dull brown darkening with age, but active spore-producing pores have a richer colour (Fig 2). The pores are almost circular, 100[lm in diameter and 5-6 to the mm; the dissepiment edges are woolly fibrous, slightly dentate under the microscope, and they vary in thickness from 100to 200 urn in the main part of the hymenium. The inside of old pores is stuffed with white mycelium. If a section is taken through the basidiocarp, it will be seen that the pores of the current year are clear but those of earlier years are stuffed with hyphae. The spores are colourless, non-amyloid, and acyanophilic, 4-5 x 2-6 [lm. The hymenial setae are rather simple, thick-walled short and sharply pointed, 20-30 [lm long. The hyphal system is dimitic, the generative hyphae without clamps, a feature of the genus. The skeletal hyphae are reported to be parallel in the trama of the hymenium. The authors have found this to be difficult to observe. The required thin section is difficult to obtain without a microtome. However, the feature can be observed with a good quality stereoscopic microscope, using incident light on an exposed portion of hymenium cut parallel to the pore axis. The only other species in the genus with parallel tramal hyphae is P laevigatus, which is a resupinate species associated with birch (Betula spp.) and differing in other significant respects from P tremulae.
Phellinus tremulae is a serIOUS parasite of Aspen, where it causes white rot. It is well known in Fennoscandia, and also occurs in Northern Europe, Northern Asia and North America where Aspen is a common component of the northern temperate and boreal forests. It is also reported to parasitise White Poplar (P alba) and Grey Poplar (P x canescens) in Fennoscandia, but so far the authors have only found it on P tremula and not on other poplar species in Badenoch & Strathspey. In Fennoscandia it is mostly known from large old trees, with basidiocarps occurring from 2 to 10 metres above the ground. The authors have found that the fungus is not confined to old and large specimens of P tremula. Measurements of 54 infected trees in woodlands of Badenoch and Strathspey show it to be present on apparently young trees as small as 65 em circumference at breast height. The basidiocarps have been found as low as 60 em above the ground, much lower than reported for trees in Fennoscandia. They are found on standing and fallen trees and the fungus is reported to continue to grow for some years on dead trees. Attached dead branches and rot holes are reported to act as channels for infection of the living tree with basidiocarp formation close to a scar or snag. This is not always obvious, in the trees seen by the authors some arise directly from apparently undamaged areas of the tree boles. A sample provided for the Royal Botanic Gardens, Kew is in culture and the culture has the sweet smell of Oil of Wintergreen, noted by Niemala (1974). The authors wish to thank Prof. L. Ryvarden (Oslo), for his confirmation of the identification of the fungus, Dr. E. M. Saunders (RBG Kew) for successfully getting the species into culture, Dr. T. Niemala for helpful comments and copies of his papers, Mr A. Henrici for drawing Niemala's paper to our attention, and the RSPB for their cooperation. References Niemala, T. (1974) On Fennoscandian Polypores. III Phellinus tremulae (Bond.) Bond. & Borisov Ann. Bot. Fennici 11: 202-215. Ryvarden 1. & Gilbertson R. 1. (1994) European Polypores, Part 2; Fungiflora, Oslo.