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Meripilus sumstinei is a large, parasitic and saprobic polypore mushroom known for its distinctive black-staining reaction when bruised or cut. It typically grows in large, overlapping clusters at the base of hardwood trees or from buried roots, causing a white rot.
How to Identify
- Cap
- Individual caps are typically 10-30 cm wide, fan-shaped or spatulate, with a wavy or lobed margin. The surface is initially pale tan to yellowish-brown, becoming darker brown to grayish-brown with age. It is often finely velvety or scaly, especially when young. The most crucial identifying feature is that the cap surface, especially the pore surface, will stain black when bruised or handled.
- Gills
- Absent. Instead, it has a pore surface on the underside of the caps. The pores are very small (3-5 per millimeter), angular to round, and initially white or cream, turning yellowish with age. They stain black almost immediately upon bruising.
- Stem
- Typically absent or very rudimentary, appearing as a thick, central stalk-like base from which the individual caps arise. This base is usually buried or partially buried in the substrate (wood or soil).
- Flesh
- Thick, tough, and fibrous, especially in mature specimens. It is whitish to pale cream, but quickly stains black when cut or bruised. This black-staining reaction is a key diagnostic feature.
- Fruiting body
- Large, fan-shaped to spatulate caps arranged in overlapping, rosette-like clusters, often reaching impressive sizes (up to 50-100 cm or more across). The entire cluster can weigh several kilograms.
- Habitat
- Grows at the base of living or dead hardwood trees (especially oak, maple, beech) or from buried roots. It is both parasitic, causing a white rot in living trees, and saprobic, decomposing dead wood.
Key Facts
- Cap surfaces: Finely velvety to scaly, becoming smoother with age; pale tan to brown, staining black when bruised.
- Growth Form: Large, overlapping, rosette-like clusters.
- Spore Print: White.
- Body color: Whitish to pale cream flesh, staining black; pore surface white to yellowish, staining black.
- Odor: Mild, pleasant, mushroomy.
- Flesh bruises: Stains black almost immediately upon cutting or bruising.
- Height: Individual caps 10-30 cm wide; entire cluster can be 50-100 cm or more across.
- Cap Diameter: 10-30 cm for individual caps.
- Nutrient gathering: Parasitic on living hardwood trees, saprobic on dead wood and buried roots.
Safe
SafeMeripilus sumstinei is generally considered edible when young and tender, but it can cause gastrointestinal upset in some individuals, especially if consumed in large quantities or if older, tougher parts are eaten. It is not known to contain any deadly toxins, but individual sensitivities vary. Always cook thoroughly.
Quick Check
- Odor: Mild, mushroomy, sometimes slightly acidic or earthy.
- Fruiting: Late spring to late fall, most common in late summer and early fall.
- Substrate: Base of hardwood trees (especially oak, maple, beech) or from buried roots.
Where to Find
Eastern North America
Common throughout the eastern United States and Canada.
Midwestern United States
Frequently found in deciduous forests of the Midwest.
Europe
A closely related species, Meripilus giganteus, is found in Europe, which was once considered the same species but is now recognized as distinct. Meripilus sumstinei is primarily a North American species.
Finding Tips
Look for Hardwood Trees
Focus your search around the base of large, mature hardwood trees, particularly oaks, maples, and beeches. It often grows from buried roots, so look for clusters emerging from the ground near trees.
Check for Staining
Gently bruise a small part of the pore surface or cut a small piece of the flesh. If it stains black within a few minutes, it's a strong indicator of Meripilus sumstinei.
Seasonal Timing
While it can appear from late spring to fall, it is most commonly found in late summer and early fall after periods of rain.
Size Matters
These mushrooms can grow to be very large, so they are often quite conspicuous once you know what to look for.
Similar Species
Hen of the Woods
Polypore mushroom
Also known as: Maitake, Grifola frondosa
Berkeley's Polypore
Polypore mushroom
Also known as: Bondarzewia berkeleyi
Giant Polypore
Polypore mushroom
Also known as: Meripilus giganteus
Scientific Classification
- Phylum
- Basidiomycota
- Class
- Agaricomycetes
- Order
- Polyporales
- Family
- Meripilaceae
- Genus
- Meripilus
Storage Information
- Max Temperature: 4°C
- Freezing duration: 6 months
- Min Temperature: 0°C
- Refrigeration: 5 days
How to Clean
Due to its large size and tendency to grow close to the ground, Meripilus sumstinei can accumulate debris. Brush off any dirt, leaves, or insects with a soft brush or damp cloth. Avoid washing extensively under running water as it can become waterlogged. Trim away any tough, woody portions, especially from older specimens, as only the tender edges are typically palatable.
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