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Summary: member of Armillaria mellea group, which is difficult to separate macroscopically; features of this species include relatively small size, tan to pinkish brown cap that is distinctly hairy, frequently enlarged stem base which sometimes stains yellow when bruised, white cobwebby veil at stem top, hardwood habitat (usually on soil but sometimes "climbing" onto logs or stumps); usually does not harm trees to any extent; found at least BC (Morrison), WA (Banik), OR, CA, Mexico, (Baumgartner); the most widely distributed species east of the Rocky Mountains, including the northeast, midwest, and gulf coast, but is very rare in the west, (Volk), also in Europe and North Africa (Courtecuisse)
Cap: up to 10cm across, ochraceous brown to brownish; fine yellow brown to grayish brown scales, margin not very striate, slightly fleecy, (Courtecuisse), tan to pinkish brown; distinctly hairy, (Berube), reddish brown to pinkish ocher with brown scales at center, (Kibby)
Flesh: firm; whitish, (Buczacki)
Gills: subdecurrent [somewhat decurrent], spotted white to brownish, (Courtecuisse), cream to pinkish buff (Kibby)
Stem: up to 12cm long and up to 2.5cm wide, often bulbous club-shaped; +/- bister, brown in lower part; with bright to grayish yellow fibrils or fleecy scales, (Courtecuisse), base is commonly swollen and sometimes stains yellow where bruised, (Volk), club-shaped to cylindric; rhizomorphs cylindrical with monopodial branching, (Berube), bulbous; pinkish buff, often with a yellow coating at the base, (Kibby)
Veil: ring fibrillose and short-lived (Courtecuisse), cortinate, unpigmented, evanescent [fleeting], (Berube), white, cobwebby veil at stem apex, unlike the thick woolly ring of A. mellea, (Kibby), partial veil is cortinaceous, i.e. similar to the cobwebby cortina of a Cortinarius species, leaving white arachnoid remnants on stem, (Volk)
Odor: faint, mushroomy, fruity, (Buczacki)
Taste: faint, bitter, (Buczacki)
Microscopic spores: spores 7.2-9.5 x 4.8-6 microns, (Volk), clamp connections present on basidia; subhymenial tissue binucleate, pigments in cell wall and in vacuoles, (Berube), spores 7.5-8.5 x 4.5-5 microns, smooth, (Kibby)
Spore deposit: white (Kibby)
Habitat / Range
single to gregarious, usually on soil, but occasionally "climbing" onto logs or stumps to fruit, almost always found on hardwoods, but occasionally on conifers, (Volk), Garry oak habitat on southern Vancouver Island, (Allen), often occurs singly, parasitic or saprophytic; on the ground, but connected to wood by rhizomorphs, (Courtecuisse), rarely grows in clumps but scattered singly over a wide area growing from buried wood or roots, (Kibby), fall (Buczacki)
so similar to Armillaria cepistipes that microscope needed: the hyphal cells of the cap scales of A. bulbosa (Barla) Kile and Watl. are said to be 38-72 microns long, usually with a considerable number (10-55%) over 60 microns long, whereas the hyphae of the cap scales of Armillaria cepistipes Velen. are 25-50 microns long, (Breitenbach); Armillaria sinapina has some cells in annulus greater than 8 microns, whereas Armillaria gallica has no cells in annulus greater than 8 microns, (Volk)
Recommended citation: Author, Date. Page title. In Klinkenberg, Brian. (Editor) 2019. E-Flora BC:
Electronic Atlas of the Plants of British Columbia [eflora.bc.ca]. Lab for
Advanced Spatial Analysis, Department of Geography, University of British
Columbia, Vancouver. [Accessed:
18/11/2019 5:19:50 AM
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