When: 2008-03-26

Collection location: Edgewood Blue, Wells Gray region, British Columbia, Canada [Click for map]

Who: Jason Hollinger (jason)

Specimen available

I’ve seen what I thought was a single species growing on both cottonwood (Populus trichocarpa) and aspen (P. tremuloides), but it seems that the one on cottonwood (pictured here) is Phellinus igniarius and the one on aspen is P. tremulae. There are subtle differences. Please someone correct me where I’m wrong:

P. igniarius: larger, on a large number of hardwood hosts, undersurface nearly parallel to ground1, spores larger (5.8+/-0.2 × 5.0+/-0.2 um2), hymenial setae rare to abundant and smaller.

P. tremulae: smaller, exclusively on aspen (both P. tremuloides and P. grandidentata according to Tom Volk3), undersurface 45 degrees1, spores smaller (5.1+/-0.2 × 4.2+/-0.2 um2), hymenial setae always present and larger1.

While it was a tough job finding any spores at all, I measured 5 on mine to be (5.0)5.5(6.1) x (3.6)4.0+(4.5) um Q=(1.3)1.3(1.4), and observed no setae in any of my sections. I take this as verification of the tentative ID based on host tree alone as P. igniarius s. s.

1 CTD for P. igniarius. CTD for P. tremulae.

2 I. Sell 2006.

3 Tom Volk’s Fungus of the Month, February 2004.

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