Meripilussumstinei(Murrill) M. J. Larsen & Lombard
[not Meripilus giganteus of Eurasia]
Epithet = named in honor of collector David Ross Sumstine (1870 - 1965). Genus = a part - pileus (cap in parts).
Large compound fruitbody formed of overlapping caps. Caps 5–20 cm wide, whitish to yellowish brown, may be radially streaked or zoned. Pore surface whitish to light brown or darkening; pores small, 3–5 per mm (apparently 6–8 per mm when dried).
Upper and lower sides bruising black after handling or with age. The short basal stem may become black and tuberous.
Texture is very fibrous; easily splitting radially.
Odor mild. Spore print white. Hyphal system monomitic; clamp connections absent.
None of the similar species bruise black. Grifola frondosa has smaller lobed fronds, grayish to brownish and white pores; pores are 2–4 per mm. Laetiporus species have brighter coloration. Bondarzewia is cream-colored and thick-fleshed with larger pores (1–2 per mm), caps not streaked; spores with amyloid ornamentation.
Saprobe and probably parasitic, on hardwoods at bases of trees, roots, and stumps, causing a white rot. Often with oak, also recorded for beech and hickory. Some reports in the west are with conifers, such as Douglas-fir.
Summer and fall; July to mid October in Chicago Region.
Widely distributed in eastern North America, less common in the west.
Chicago Region status
Uncommon. Recorded in widely scattered locations of six counties across the region. Surprisingly not documented for the much-studied Cook County until twice in 2015.
Six collections from five counties plus specimen at Morton Arboretum, DuPage County.
Taxon Details and Links
Meripilussumstinei(Murrill) M. J. Larsen & Lombard,
Mycologia 80: 615 (1988)
Bulletin of the Torrey Botanical Club 31 (6): 335 (1904)
Larsen, M. J., F. F. Lombard. 1988. The status of Meripilus giganteus (Aphyllophorales, Polyporaceae) in North America.
Mycologia 80(5): 612–21. DOI: 10.2307/3807709
[PDF available from Forest Service]