Brown Cubical Sap Rot

Gleophyllum sepiarium (Wulfen:Fr.) P. Karst.
(= Lenzites saepiaria (Wulfen:Fr.) Fr.)

Basidiomycotina, Aphyllophorales, Polyporaceae

Hosts:Gleophyllum sepiarium is found primarily on dead conifer wood, less commonly on hardwoods. In B.C., it has been reported on amabilis, grand, and subalpine fir, white, black, Engelmann, and Sitka spruce, lodgepole, ponderosa, and western white pine, Douglas-fir, western redcedar, western hemlock, red alder, paper birch, aspen, and cherry. Elsewhere in North America it is also found on western larch, mountain hemlock, cypress, incense and yellow cedar, juniper, giant sequoia, apple, arbutus, elm, oak, sweet-gum, tulip-tree, and willow.

Distribution: This fungus is widely distributed on dead trees and slash throughout the range of its hosts in B.C.

Identification: The fruiting bodies are small, annual, leathery, shelf-like structures that generally form in cracks and checks on fallen logs (Figs. 48a, 48b). Occasionally, fruiting bodies are stalked. The upper surface is light-to-dark cinnamon brown, zoned, at first velvety but becoming roughened with maturity. The lower surface is light brown and consists of tough, radiating lamellae or gill-like structures (15-20/cm, counted at margin) (Fig. 48c). The context is brown.

The decay appears first as yellow to yellow-brown pockets of discoloration in the sapwood or outer heartwood. The advanced decay is a typical brown cubical rot, with yellow to yellow-brown mycelial felts in the shrinkage cracks.

Microscopic Characteristics: Hyphae in the context of the fruiting body are of three types: generative hyphae thin to thick-walled with clamps, skeletal hyphae (most common) thick-walled, up to 6.0 µm in diameter, binding hyphae golden-coloured, tortuous, rare. Basidiospores cylindrical, hyaline, smooth, IKI-, 9-13 x 3-5 µm. Growth in culture slow, mat at first white then yellow-brown, laccase negative, clamps, frequent arthroconidia. Stalpers: (2) (4) (7) (8) (9) (11) 13 (14) (15) (17) 18 (21) 22 24 (25) (26) 30 31 34 35 (37) (38) (39) 40 42 (44) (45) (46) 48 50 (51) 52 53 (54) (61) 67 (75) 83 84 85 (89) (90) (93) (95) (96) 98 100.

Damage: Extensive decay is indicated by the presence of fruiting bodies. Where conks are numerous, the entire sapwood and some heartwood should be considered unusable for lumber or pulp. Decay may also occur on wood in service, for example fence posts or other wooden structures.

Remarks: This fungus is occasionally found on living trees, and on dead sapwood under scars, but most commonly on fire-killed trees and slash. The fruiting bodies of G. sepiarium could be confused with T. abietinum, but the latter has fewer (8-13/cm) and coarser gills. Other related species of Gloeophyllum have a more pore-like hymenial surface rather than gills.

References:

Gilbertson, R. L. and L. Ryvarden. 1986. North American Polypores. 1:310. Fungiflora, Oslo.

Figures

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Figure 48a: Fruiting bodies of G. sepiarium.

 Figure48b: Fruiting bodies of G. sepiarium.

 Figure 48c: The spore-producing surface of G. sepiarium forms radiating lamellae.