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A re-examination of Fomes lignosus and Polyporus zonalis
[ 426 ] A RE-EXAMINATION OF FOMES LIGNOSUS AND
POLYPORUS ZONALIS By B. K. BAKSHI, SUJAN SINGH
AND
BALWANT SINGH
Forest Research Institute, Dehra Dun, India (With Plate 27 and
I
Text-figure)
Fomes lignosus (Klotzsch) Bres. and POlypoTUS zonalis Berk., both occurring parasitically and saprophytically, are described from sporophores and cultures. F. lignosus is orange-red on the upper surface with orange-yellow margin and orange-red pore tubes fading towards the context. In P. zonalis the surface is pale to pinkish with white pore tubes. The presence of mucronate cystidia in the sporophore and of fibre hyphae and conidia in cultures distinguishes F. lignosus from P. zonalis in which they are absent. The latter, however, develops incrusted cystidia in the sporophore and clamped hyphae and acanthophyses in culture, all absent from F. lignosus.
Further studies have shown that the fungus described by Bose & Bakshi (1957) as Polyporus lignosus ( = Fomes lignosus) from root and butt ofliving Bauhinia purpurea and Ficus bengalensis is in reality P. zonalis, The fact that this fungus was described as producing rhizomorphs in culture and white pocket rot in the heartwood led Fox (1961) to state that he believed that Bose & Bakshi were dealing with the P. zonalis complex, since F. lignosus does not produce rhizomorphs in culture and it causes an undifferentiated white rot. A re-examination of the two species was therefore made from fresh collections. In the course of a disease survey Polyporus eonalis was encountered as a parasite of many tree species, including teak, and was also found fruiting on dead stumps. Fomes lignosus was collected on logs of Nauclea jageana from South Andamans. The latter was compared with the syntype of F. lignosus received from U ppsala, Sweden, and with sporophores and a culture identified as F. lignosus sent from the Rubber Research Institute, Ceylon. A duplicate collection of P. zonalis was received from the Royal Botanic Gardens, Kew, where Berkeley's type material is located. A culture of this species was sent to Dr Mildred K. Nobles, who observed that it compared with her isolates of this species. Our thanks are due to co-operation of all institutions and workers in this study. The descriptions given below are composite descriptions based on the type material, fresh collections and cultures. POLYPORUs ZONA LIS
Sporophores substipitate to sessile, usually attached by a narrow base, dimidiate to flabelliform, usually imbricate, leathery when fresh, hard and rigid when dry, 0'S-7 x I-S x o- 1-0'S em.; surface pale or pinkish buff when young, becoming reddish brown with age, concentrically zonate
Fornes lignosus and Polyporus zonalis. B. K. Bakshi et al.
427
(PI. 27, fig. 2), tomentose, becoming somewhat glabrous and with radiating wrinkles on drying, margin thin or rounded, incurved on drying; context white or light coloured, fibrous, up to 4 mm. thick; hymenial surface (PI. 27, fig. I) white to pinkish (' Pale Ochraceous Salmon' to 'Pinkish buff'), with a silky sheen, with up to 3 mm. sterile margin; pores round, oval to somewhat angular, 7-9 per mm., pore tubes concolorous with the context or slightly deeper, up to 2'5 mm.long; basidia clavate to subclavate (Text-fig. I, I), 6-1OfL broad; basidiospores hyaline, subglobose to globose,
f! 1
3~ o 000=== . 0 () ~~[~==~:=_~_~_=_= 2
:
~~~~~~II~~
5
=-----------------
Text-fig. 1. Polyporus zonalis. I, Basidium; 2, basidiospores; 3, cystidium; 4, thinwalled hypha; 5, thick-walled hyphae (all from sporophores); 6, hypha with clamp; 7, acanthophysis; 8, thick-walled hypha; 9, thin-walled hypha with clamps (all from cultures; 8 and 9 from fruit-body in culture). Fornes lignosus. 10, Basidium; II, mucronate cystidia; 12, thin-walled hypha (all from sporophores); 13, thin-walled hypha; 14, fibre hypha from rhizomorphic strands; 15, conidia (all from cultures). All x 1500.
apiculate, r-guttulate (Text-fig. I, 2), always found in the sporophores, 3'5-4'7 fL diam.; rystidia clavate, incrusted or capitate-incrusted (Textfig. I, 3) or rarely with short projections (acanthophyses), more prominent in fresh specimens, thin to slightly thick-walled, 6-13fL diam.; hyphae hyaline, of two types (a) thin-walled or slightly thicker-walled, simple septate, rarely branched (Text-fig. I, 4); (b) thick-walled with lumen usually narrow or obliterated (Text-fig. 1,5), simple septate, 7'3-10 fL diam. Type ofrot. White pocket rot, distinct when fresh, thin indistinct strands on the wood just beneath the sporophores.
428
Transactions British Mycological Society
Cultural characters. (a) Radial growth 4-5 em. in 7 days on malt agar at 25° C. Advancing zone even, white, with aerial mycelium extending to the periphery in the form of thick strands (PI. 27, fig. 6), forming a white to cream fruit-body with regular pores, usually at the end of the rhizomorphic strands along the wall of the Petri dish in 3-4 weeks; mat white, appressed cottony to cottony-woolly to silky with prominent rhizomorphic strands, zonate or not, white irregular lines representing cuticular cells develop on mat and on reverse; reverse bleached. On gallic acid medium, diffusion zones moderately strong, growth nil; on tannic acid medium, diffusion zones moderately strong to strong, growth 1.5-2.5 em. in 6 days; on gentian violet, growth moderate, medium discoloured in two weeks. (b) Mycelial characters. Advancing zone hyphae hyaline, thin to slightly thick-walled, usually simple septate, with rare but prominent clamps (Text-fig. I, 6), branched, 3-8 iL broad, hyphal swellings both intercalary and apical. Aerial mycelium with: (a) hyphae as in the advancing zone; (b) cuticular cells develop irregularly, forming pseudoparenchyma ; (c) acanthophyses which are clavate, thin-walled, and densely covered with projections (Text-fig. I, 7), up to 60JL long; and (d) hyphae with irregular projections. In the sporophores formed in culture basidia are clavate to subclavate, 6--9 iL broad; basidiospores hyaline, globose to subglobose, apiculate, one-guttulate, 3'5-4.6 JL diam.; acanthophyses thin to slightly thick-walled, up to 10JL broad; and (d) hyphae (i) thin to slightly thick-walled, branched, wall sometimes incrusted, simple septate, commonly 3-6'5 JL broad, (ii) thick-walled with lumen narrow or obliterated (Text-fig. I, 8), up to 10 JL broad, and (iii) thin-walled, branched, septate with clamp connexions (Text-fig, I, 9), Submerged hyphae are hyaline, thin-walled, simple septate, some being swollen at the tip to form short knob-like structures bearing many spines. In a personal communication Dr Nobles informed us that she observed cuticular cells and acanthophyses in her isolates of P, zonalis. Specimens andcultures examined. On living Sapindus emarginatus, Dehra Dun, Forest Research Institute (FRI) 7190 (Oct. 1959), FRI 7366 (July 1960) and its spore culture FRI 599, FRI 7393 (Sept. 1960); on living and dead Tectona grandis, Dehra Dun, FRI4191 (March 1946), FRI7289 (Sept. 1958), FRI7200 (Sept. 1959) and its spore culture FRI 600; on living Bauhinia purpurea, Dehra Dun, FRI 6549 (Aug. 1955) and its spore culture FRI 309; on living Sy.rygium cumini, Dehra Dun; on living Ficus bengalensis, Dehra Dun, FRI5471 (July 1949) and its spore culture FRI41O; on dead stump of Areca palm, Bengal, FRI2307 (Sept. 1938); on dead Dalbergia sissoo, Dehra Dun; on dead bamboo, Bengal, FRI2308 (July 1933), FRI6563 (Aug. 1952), Dehra Dun, FRI3552 (Nov. 1942), FRI3950 (Aug. 1945); on dead Artocarpus, South Andamans, FRI7278 (Feb. 1960) and its spore culture FRI 602; Botanic Gardens, Singapore, received from Herb, Kew, 184 (colI. F. M. Burkill, Oct. 1913) FRI7256. FOMES LIGNOSUS
Sporophores usually annual, rarely perennial, sessile, attached by broad base, effuso-reftexed, rarely resupinate, applanate to dimidiate, usually
Fornes lignosus and Polyporus zonalis. B. K. Bakshi et al. 429 imbricate, leathery when fresh, hard and rigid on drying, 4-22 x 3-9 X 0'3-1 '5 em.; surface deep orange-red when active, reddish brown to yellowish brown on drying, with irregular fused and distinctly zoned patches of pilei, narrowly concentrically zonate (PI. 27, fig. S), with thin crust, tomentose, becoming glabrous on drying, margin bright yellow when fresh, fading on drying, thin or rounded, usually strongly incurved on drying; context cream coloured, corky up to I em. thick towards the base, hymenial surface (PI. 27, fig. 3) orange-red when fresh, reddish brown on drying, with up to 4 mm. sterile margin; pores round, oval or sometimes angular, 6-9 per mm., pore tubes concolorous below, pale towards the context, up to 6 mm.long; basidia and basidiospores (Text-fig. I, 10) rarely seen; cystidia mucronate, bulbous at the base (Text-fig. I, II), thin-walled, deeply staining, found in the hymenium as well as embedded, 5-10 fL; hyphae hyaline, thin or slightly thick-walled, septate, branched (Text-fig. I, 12), 3'4-4'6fL broad. Thick branched rhizomorphs (PI. 27, fig. 4) are attached to sporophore and also occur on the wood. Cultural characters. (a) Radial growth S-S'S em. in 7 days at 2So C. on malt agar. Advancing zone even, white, with aerial mycelium extending to the periphery; mat white, sometimes developing brown coloration in patches, turning orange brown (' Light Ochraceous Salmon ') in very old cultures, appressed subfelty to silky, to cottony-felty, zonate or not (Pl. 27, fig. 7), prominent, profusely branched, rhizomorphic strands formed on the lid of the Petri dish in old cultures, odour nil, reverse bleached. On gallic acid medium, diffusion zones moderately strong, growth nil; on tannic acid medium, diffusion zones moderately strong to strong, radial growth 1'5-1 '8 em. in 7 days at 2So C.; on gentian violet growth moderate, medium discoloured in 4 weeks, forming prominent zonations. (b) Mycelial characters. Advancing zone hyphae hyaline, simple septate, thin to slightly thick-walled, branched (Text-fig. I, 13) 3-6 fL broad. Aerial mycelium with: (i) hyphae as in the advancing zone; (ii) cuticular cells, irregular, forming a pseudoparenchyma in old cultures; (iii) fibre hyphae in rhizomorphic strands formed on the glass surface, rarely septate (Text-fig. I, 14), up to 2'SfL broad; (iv) swellings both intercalary and apical, sometimes appearing like chlamydospores; and (v) conidia pleurogenous (Text-fig. I, IS), hyaline, subglobose to ovoid with slightly rough walls when old, I'S-3'7 x 1-3'3 fL· Submerged hyphae as in the advancing zone. Specimens and cultures examined. On logs of Nauclea jageana, South Andamans, FRI 7281 (Feb. 1960) and its context cultures FRI603 and 604; Jungle wood, South India, FRI4243 (Jan. 1946); on Hevea, Rubber Research Institute, Ceylon, FRI 7S02, context cultures RRIC IO (FRI 616), RRIC 32 (FRI 617); Uppsala (Sweden), FRI 6623, syntype. F. lignosus can thus be distinguished from P. zonalis by many features. In the sporophore of F. lignosus the surface is orange red with an orange yellow margin when fresh and pore tubes fade towards the cream-coloured context. Occurrence of fused pilei on the surface is characteristic. In P. zonalis, on the other hand, the surface is pale to pinkish, and both context and pore tubes are uniformly white. Microscopically, F. lignosus can be easily distinguished by the presence ofmucronate cystidia in the hymenium
430
Transactions British Mycological Society
and absence of incrusted cystidia and thick-walled hyphae with obliterated lumen, which are present in the sporophore of P. zonalis. The incrustations on the cystidia of P. zonalis are deciduous, so that they are not observed in old collections, though cystidial hyphae without incrustation may be seen. Sporophores of P. ;::onalis are usually fertile and basidiospores may be found even in herbarium specimens. In F. lignosus, basidiospores may be seen in fresh material but are normally absent from dry. In culture P. zonalis is characterized by the presence of acanthophyses, prominent clamps and the formation of sporophores. These characters are lacking in cultures of F. lignosus in which fibre hyphae and conidia develop and these are lacking in cultures of P. zonalis. REFERENCES
BOSE, S. R. & BAKSHI, B. K. (1957)' Polyporus lignosus Klotzsch and its identity. Trans. Brit. mycol. Soc. 40, 456-460. Fox, R. A. (1961). White root disease of Hevea brasiliensis: the identity of the pathogen. Proc. nat. Rubb. Res. Coif. pp. 473-482.
EXPLANATION OF PLATE
27
Polyporus zonalis Figs. 1,2. Fresh sporophores ofFRI 7366. I, Lower surface; 2, upper surface showing weak zonations. 6. Spore culture (FRI 599), 10 days old.
Fornes lignosus Figs. 3-5. Dried sporophores ofFRI 7281. 3, Lower surface; 4, rhizomorphs; 5, upper surface showing strong zonations and fused pilei. 7, context culture (FRI 603),!IO days'old. All x 0'5.
(Accepted for publication 19 December 1962)
Trans. Brit. mycol. Soc.
Vol. 46, Plate 27
(Facing p. 430)
POLYPORUS ZONALIS By B. K. BAKSHI, SUJAN SINGH
AND
BALWANT SINGH
Forest Research Institute, Dehra Dun, India (With Plate 27 and
I
Text-figure)
Fomes lignosus (Klotzsch) Bres. and POlypoTUS zonalis Berk., both occurring parasitically and saprophytically, are described from sporophores and cultures. F. lignosus is orange-red on the upper surface with orange-yellow margin and orange-red pore tubes fading towards the context. In P. zonalis the surface is pale to pinkish with white pore tubes. The presence of mucronate cystidia in the sporophore and of fibre hyphae and conidia in cultures distinguishes F. lignosus from P. zonalis in which they are absent. The latter, however, develops incrusted cystidia in the sporophore and clamped hyphae and acanthophyses in culture, all absent from F. lignosus.
Further studies have shown that the fungus described by Bose & Bakshi (1957) as Polyporus lignosus ( = Fomes lignosus) from root and butt ofliving Bauhinia purpurea and Ficus bengalensis is in reality P. zonalis, The fact that this fungus was described as producing rhizomorphs in culture and white pocket rot in the heartwood led Fox (1961) to state that he believed that Bose & Bakshi were dealing with the P. zonalis complex, since F. lignosus does not produce rhizomorphs in culture and it causes an undifferentiated white rot. A re-examination of the two species was therefore made from fresh collections. In the course of a disease survey Polyporus eonalis was encountered as a parasite of many tree species, including teak, and was also found fruiting on dead stumps. Fomes lignosus was collected on logs of Nauclea jageana from South Andamans. The latter was compared with the syntype of F. lignosus received from U ppsala, Sweden, and with sporophores and a culture identified as F. lignosus sent from the Rubber Research Institute, Ceylon. A duplicate collection of P. zonalis was received from the Royal Botanic Gardens, Kew, where Berkeley's type material is located. A culture of this species was sent to Dr Mildred K. Nobles, who observed that it compared with her isolates of this species. Our thanks are due to co-operation of all institutions and workers in this study. The descriptions given below are composite descriptions based on the type material, fresh collections and cultures. POLYPORUs ZONA LIS
Sporophores substipitate to sessile, usually attached by a narrow base, dimidiate to flabelliform, usually imbricate, leathery when fresh, hard and rigid when dry, 0'S-7 x I-S x o- 1-0'S em.; surface pale or pinkish buff when young, becoming reddish brown with age, concentrically zonate
Fornes lignosus and Polyporus zonalis. B. K. Bakshi et al.
427
(PI. 27, fig. 2), tomentose, becoming somewhat glabrous and with radiating wrinkles on drying, margin thin or rounded, incurved on drying; context white or light coloured, fibrous, up to 4 mm. thick; hymenial surface (PI. 27, fig. I) white to pinkish (' Pale Ochraceous Salmon' to 'Pinkish buff'), with a silky sheen, with up to 3 mm. sterile margin; pores round, oval to somewhat angular, 7-9 per mm., pore tubes concolorous with the context or slightly deeper, up to 2'5 mm.long; basidia clavate to subclavate (Text-fig. I, I), 6-1OfL broad; basidiospores hyaline, subglobose to globose,
f! 1
3~ o 000=== . 0 () ~~[~==~:=_~_~_=_= 2
:
~~~~~~II~~
5
=-----------------
Text-fig. 1. Polyporus zonalis. I, Basidium; 2, basidiospores; 3, cystidium; 4, thinwalled hypha; 5, thick-walled hyphae (all from sporophores); 6, hypha with clamp; 7, acanthophysis; 8, thick-walled hypha; 9, thin-walled hypha with clamps (all from cultures; 8 and 9 from fruit-body in culture). Fornes lignosus. 10, Basidium; II, mucronate cystidia; 12, thin-walled hypha (all from sporophores); 13, thin-walled hypha; 14, fibre hypha from rhizomorphic strands; 15, conidia (all from cultures). All x 1500.
apiculate, r-guttulate (Text-fig. I, 2), always found in the sporophores, 3'5-4'7 fL diam.; rystidia clavate, incrusted or capitate-incrusted (Textfig. I, 3) or rarely with short projections (acanthophyses), more prominent in fresh specimens, thin to slightly thick-walled, 6-13fL diam.; hyphae hyaline, of two types (a) thin-walled or slightly thicker-walled, simple septate, rarely branched (Text-fig. I, 4); (b) thick-walled with lumen usually narrow or obliterated (Text-fig. 1,5), simple septate, 7'3-10 fL diam. Type ofrot. White pocket rot, distinct when fresh, thin indistinct strands on the wood just beneath the sporophores.
428
Transactions British Mycological Society
Cultural characters. (a) Radial growth 4-5 em. in 7 days on malt agar at 25° C. Advancing zone even, white, with aerial mycelium extending to the periphery in the form of thick strands (PI. 27, fig. 6), forming a white to cream fruit-body with regular pores, usually at the end of the rhizomorphic strands along the wall of the Petri dish in 3-4 weeks; mat white, appressed cottony to cottony-woolly to silky with prominent rhizomorphic strands, zonate or not, white irregular lines representing cuticular cells develop on mat and on reverse; reverse bleached. On gallic acid medium, diffusion zones moderately strong, growth nil; on tannic acid medium, diffusion zones moderately strong to strong, growth 1.5-2.5 em. in 6 days; on gentian violet, growth moderate, medium discoloured in two weeks. (b) Mycelial characters. Advancing zone hyphae hyaline, thin to slightly thick-walled, usually simple septate, with rare but prominent clamps (Text-fig. I, 6), branched, 3-8 iL broad, hyphal swellings both intercalary and apical. Aerial mycelium with: (a) hyphae as in the advancing zone; (b) cuticular cells develop irregularly, forming pseudoparenchyma ; (c) acanthophyses which are clavate, thin-walled, and densely covered with projections (Text-fig. I, 7), up to 60JL long; and (d) hyphae with irregular projections. In the sporophores formed in culture basidia are clavate to subclavate, 6--9 iL broad; basidiospores hyaline, globose to subglobose, apiculate, one-guttulate, 3'5-4.6 JL diam.; acanthophyses thin to slightly thick-walled, up to 10JL broad; and (d) hyphae (i) thin to slightly thick-walled, branched, wall sometimes incrusted, simple septate, commonly 3-6'5 JL broad, (ii) thick-walled with lumen narrow or obliterated (Text-fig. I, 8), up to 10 JL broad, and (iii) thin-walled, branched, septate with clamp connexions (Text-fig, I, 9), Submerged hyphae are hyaline, thin-walled, simple septate, some being swollen at the tip to form short knob-like structures bearing many spines. In a personal communication Dr Nobles informed us that she observed cuticular cells and acanthophyses in her isolates of P, zonalis. Specimens andcultures examined. On living Sapindus emarginatus, Dehra Dun, Forest Research Institute (FRI) 7190 (Oct. 1959), FRI 7366 (July 1960) and its spore culture FRI 599, FRI 7393 (Sept. 1960); on living and dead Tectona grandis, Dehra Dun, FRI4191 (March 1946), FRI7289 (Sept. 1958), FRI7200 (Sept. 1959) and its spore culture FRI 600; on living Bauhinia purpurea, Dehra Dun, FRI 6549 (Aug. 1955) and its spore culture FRI 309; on living Sy.rygium cumini, Dehra Dun; on living Ficus bengalensis, Dehra Dun, FRI5471 (July 1949) and its spore culture FRI41O; on dead stump of Areca palm, Bengal, FRI2307 (Sept. 1938); on dead Dalbergia sissoo, Dehra Dun; on dead bamboo, Bengal, FRI2308 (July 1933), FRI6563 (Aug. 1952), Dehra Dun, FRI3552 (Nov. 1942), FRI3950 (Aug. 1945); on dead Artocarpus, South Andamans, FRI7278 (Feb. 1960) and its spore culture FRI 602; Botanic Gardens, Singapore, received from Herb, Kew, 184 (colI. F. M. Burkill, Oct. 1913) FRI7256. FOMES LIGNOSUS
Sporophores usually annual, rarely perennial, sessile, attached by broad base, effuso-reftexed, rarely resupinate, applanate to dimidiate, usually
Fornes lignosus and Polyporus zonalis. B. K. Bakshi et al. 429 imbricate, leathery when fresh, hard and rigid on drying, 4-22 x 3-9 X 0'3-1 '5 em.; surface deep orange-red when active, reddish brown to yellowish brown on drying, with irregular fused and distinctly zoned patches of pilei, narrowly concentrically zonate (PI. 27, fig. S), with thin crust, tomentose, becoming glabrous on drying, margin bright yellow when fresh, fading on drying, thin or rounded, usually strongly incurved on drying; context cream coloured, corky up to I em. thick towards the base, hymenial surface (PI. 27, fig. 3) orange-red when fresh, reddish brown on drying, with up to 4 mm. sterile margin; pores round, oval or sometimes angular, 6-9 per mm., pore tubes concolorous below, pale towards the context, up to 6 mm.long; basidia and basidiospores (Text-fig. I, 10) rarely seen; cystidia mucronate, bulbous at the base (Text-fig. I, II), thin-walled, deeply staining, found in the hymenium as well as embedded, 5-10 fL; hyphae hyaline, thin or slightly thick-walled, septate, branched (Text-fig. I, 12), 3'4-4'6fL broad. Thick branched rhizomorphs (PI. 27, fig. 4) are attached to sporophore and also occur on the wood. Cultural characters. (a) Radial growth S-S'S em. in 7 days at 2So C. on malt agar. Advancing zone even, white, with aerial mycelium extending to the periphery; mat white, sometimes developing brown coloration in patches, turning orange brown (' Light Ochraceous Salmon ') in very old cultures, appressed subfelty to silky, to cottony-felty, zonate or not (Pl. 27, fig. 7), prominent, profusely branched, rhizomorphic strands formed on the lid of the Petri dish in old cultures, odour nil, reverse bleached. On gallic acid medium, diffusion zones moderately strong, growth nil; on tannic acid medium, diffusion zones moderately strong to strong, radial growth 1'5-1 '8 em. in 7 days at 2So C.; on gentian violet growth moderate, medium discoloured in 4 weeks, forming prominent zonations. (b) Mycelial characters. Advancing zone hyphae hyaline, simple septate, thin to slightly thick-walled, branched (Text-fig. I, 13) 3-6 fL broad. Aerial mycelium with: (i) hyphae as in the advancing zone; (ii) cuticular cells, irregular, forming a pseudoparenchyma in old cultures; (iii) fibre hyphae in rhizomorphic strands formed on the glass surface, rarely septate (Text-fig. I, 14), up to 2'SfL broad; (iv) swellings both intercalary and apical, sometimes appearing like chlamydospores; and (v) conidia pleurogenous (Text-fig. I, IS), hyaline, subglobose to ovoid with slightly rough walls when old, I'S-3'7 x 1-3'3 fL· Submerged hyphae as in the advancing zone. Specimens and cultures examined. On logs of Nauclea jageana, South Andamans, FRI 7281 (Feb. 1960) and its context cultures FRI603 and 604; Jungle wood, South India, FRI4243 (Jan. 1946); on Hevea, Rubber Research Institute, Ceylon, FRI 7S02, context cultures RRIC IO (FRI 616), RRIC 32 (FRI 617); Uppsala (Sweden), FRI 6623, syntype. F. lignosus can thus be distinguished from P. zonalis by many features. In the sporophore of F. lignosus the surface is orange red with an orange yellow margin when fresh and pore tubes fade towards the cream-coloured context. Occurrence of fused pilei on the surface is characteristic. In P. zonalis, on the other hand, the surface is pale to pinkish, and both context and pore tubes are uniformly white. Microscopically, F. lignosus can be easily distinguished by the presence ofmucronate cystidia in the hymenium
430
Transactions British Mycological Society
and absence of incrusted cystidia and thick-walled hyphae with obliterated lumen, which are present in the sporophore of P. zonalis. The incrustations on the cystidia of P. zonalis are deciduous, so that they are not observed in old collections, though cystidial hyphae without incrustation may be seen. Sporophores of P. ;::onalis are usually fertile and basidiospores may be found even in herbarium specimens. In F. lignosus, basidiospores may be seen in fresh material but are normally absent from dry. In culture P. zonalis is characterized by the presence of acanthophyses, prominent clamps and the formation of sporophores. These characters are lacking in cultures of F. lignosus in which fibre hyphae and conidia develop and these are lacking in cultures of P. zonalis. REFERENCES
BOSE, S. R. & BAKSHI, B. K. (1957)' Polyporus lignosus Klotzsch and its identity. Trans. Brit. mycol. Soc. 40, 456-460. Fox, R. A. (1961). White root disease of Hevea brasiliensis: the identity of the pathogen. Proc. nat. Rubb. Res. Coif. pp. 473-482.
EXPLANATION OF PLATE
27
Polyporus zonalis Figs. 1,2. Fresh sporophores ofFRI 7366. I, Lower surface; 2, upper surface showing weak zonations. 6. Spore culture (FRI 599), 10 days old.
Fornes lignosus Figs. 3-5. Dried sporophores ofFRI 7281. 3, Lower surface; 4, rhizomorphs; 5, upper surface showing strong zonations and fused pilei. 7, context culture (FRI 603),!IO days'old. All x 0'5.
(Accepted for publication 19 December 1962)
Trans. Brit. mycol. Soc.
Vol. 46, Plate 27
(Facing p. 430)