Entoloma ferruginans

🏷️ Description

If you find yourself under the majestic oaks of coastal California during the cool, damp months of winter, you might catch a sharp, bleach-like scent wafting from the leaf litter. Follow your nose and you could stumble upon one of the state's fungal oddities — Entoloma ferruginans, also known as the Bleachy Entoloma. 🌳🍄

This distinctive mushroom, first described by Charles Horton Peck in 1895 from specimens collected beneath oak trees in Pasadena, is a fascinating study in contrasts — dark, sticky caps, ghostly gray gills that blush pink with age, and a scent as sharp as a chlorinated swimming pool. Let’s dive in! 🌊

📌 Quick Facts

• Scientific Name: Entoloma ferruginans

• Described By: Charles Horton Peck (1895)

• Common Name: Bleachy Entoloma

• Ecology: Saprobic, found under coast live oak and other oaks

• Distribution: Endemic to California

• Season: December to February

🔎 Identification

🍄 Cap: The cap of Entoloma ferruginans measures 1.97 to 3.54 inches (5 to 9 cm) across. It starts out convex to bell-shaped, later flattening into a planoconvex or broadly bell-shaped form. When fresh, it’s sticky to the touch and sports a finely streaked, very dark grayish brown to nearly black surface, eventually lightening to dark gray with age. Its margins remain smooth, without striations.

🌿 Gills: Beneath the cap, the narrowly attached, close to crowded gills begin a somber gray to dark gray and transition to a pinkish hue as the spores mature — a classic Entoloma trait. Short-gills are frequent.

📏 Stem: The stem stands 1.97 to 3.15 inches (5 to 8 cm) tall and 0.59 to 0.98 inches (1.5 to 2.5 cm) thick. It’s typically equal or more often tapering toward the base, sometimes forming a small, underground rooting portion. The surface is dry, either bald or finely silky, with colors shifting from whitish to grayish above to whitish or yellowish near the base.

🥩 Flesh: The flesh is firm and grayish, remaining unchanged when sliced.

👃 Odor & Taste: Its most arresting feature is its chlorinated, bleach-like odor — sometimes described as spicy with an iron-like tang, evocative of ferric chloride. The taste is slightly mealy or indistinct.

🧪 Spore Print & Microscopy

• Spore Print: Pink

• Spores: 6–10 × 5–9 µm; 5- to 6-sided, heterodiametric to nearly isodiametric, angular, smooth, and hyaline

• Pileipellis (Cap Cuticle): An ixocutis (a gelatinous cuticle layer) composed of hyaline to brownish hyphae in 10% ammonia, with intracellular pigment

• Hymenial Cystidia: Absent

• Clamp Connections: Present

🍂 Habitat & Ecology

Entoloma ferruginans is a saprobic species, breaking down organic matter in the rich, loamy soils under coast live oaks (Quercus agrifolia) and other oaks. It grows alone, scattered, or gregariously and is typically encountered from December to February in the cool, wet months of California's winter.

Its ecological association is not mycorrhizal, but it does tend to appear in the leaf litter-rich microhabitats favored by oak woodlands.

🍽️ Edibility

Not recommended.

Aside from its pungent bleachy odor, the edibility of Entoloma ferruginans has never been established — and given its resemblance to other toxic Entoloma species, it’s best admired rather than consumed. 🚫

👀 Look-Alikes

Its stature and dark, sticky cap may remind foragers of some species in Tricholoma, but its pinkish spore print and bleachlike odor set it apart. It can also be confused with Entoloma cinereolamellatum, though definitive identification requires DNA analysis.

Photo sources:

Photo 1 - Author: Ken-ichi Ueda (Public Domain)

Photo 2 - Author: Alan Rockefeller (CC BY-SA 4.0)

Photo 3 - Author: Cristhian Mace (CC BY 4.0)

Photo 4 - Author: Alex (CC BY 4.0)