Birch Mazegill, Gilled Polypore
Lenzites betulinus · Family Polyporaceae · Updated October 2026
3,403US records
44states
Octbusiest month
3,403 US records since 1830 (1,954 in the last 10 years)
Last seen Oct 4, 2026 (about 3 weeks ago) near Geneva, Ontario County, NY, photographed by an iNaturalist user, with the ID agreed on by other iNaturalist users (research grade). Most US records come from California, New Jersey and Pennsylvania, and the busiest months are Oct, Sep and Nov. (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: Oct, Sep, Nov.
Where it's recorded
Top counties
- Sonoma County, CA (140) · latest Mar 5, 2026
- Marin County, CA (96) · latest Sep 9, 2026
- San Mateo County, CA (81) · latest Jun 18, 2026
- Sussex County, NJ (73) · latest Oct 27, 2021
- Ocean County, NJ (69) · latest Dec 4, 2025
- Santa Clara County, CA (67) · latest May 30, 2026
- Mercer County, NJ (58) · latest May 4, 2019
- Alameda County, CA (57) · latest Jul 3, 2026
- Montgomery County, MD (56) · latest Mar 7, 2026
- Fairfax County, VA (54) · latest Dec 24, 2025
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.