Imperial Mushroom
Catathelasma imperiale · Family Biannulariaceae · Updated October 2026
49US records
13states
Augbusiest month
49 US records since 1901 (2 in the last 10 years)
Last seen Aug 10, 2019 (about 7 years ago) near St. Mary's, Clear Creek County, CO, a preserved specimen in Denver Botanic Gardens, Sam Mitchel Herbarium of Fungi. Most US records come from California, Colorado and Washington, and the busiest months are Aug, Sep and Oct. (Data as of October 26, 2026; records can lag by weeks.)
⚠ Never eat a wild mushroom based on this site. We show where fungi have been recorded, nothing more. We never say any mushroom is edible or safe, and you shouldn't decide that from any website, app or photo. Many deadly mushrooms look like harmless ones. If someone may have eaten a wild mushroom, call Poison Control at 1-800-222-1222 right away.
Lookalike warning. Many mushrooms, including deadly ones, closely resemble each other, and the only reliable identification comes from an expert looking at the actual specimen (often with spore prints or microscopy). Never use a name, photo or record count on this page to decide what something is.
When it's recorded
Records by month, all years. Busiest: Aug, Sep, Oct.
Where it's recorded
Top counties
- Humboldt County, CA (5) · latest Nov 5, 1984
- Mendocino County, CA (3) · latest Oct 15, 1989
- Coconino County, AZ (2) · latest Aug 27, 1971
- San Juan County, UT (2) · latest Nov 9, 1969
- Fremont County, WY (2) · latest Aug 11, 1999
- Valley County, ID (2) · latest Sep 10, 1979
- Adams County, ID (2) · latest Sep 5, 1964
- Taos County, NM (2) · latest Sep 4, 1994
- Pend Oreille County, WA (2) · latest Sep 23, 2004
- Sevier County, TN (2) · latest Oct 7, 2010
More on this species from GBIF.
Bring along
🍄
Regional mushroom field guideSee on Amazon🍄
Folding mushroom knife with brushSee on Amazon🍄
Wicker foraging basketSee on Amazon🍄
10x hand lens / loupeSee on Amazon🍄
Spore print paperSee on AmazonAs an Amazon Associate we earn from qualifying purchases.