Yellow Fieldcap vs Deadly Conocybe
Bolbitius titubans compared with Conocybe filaris — how to tell them apart in the field.
This is a dangerous confusion.
At least one of these species is potentially deadly. Never eat a wild mushroom based on a photo comparison alone — verify with local experts.
How to Tell Them Apart
A dangerously toxic small brown mushroom found in lawns and wood chips. Much darker brown than the bright yellow Bolbitius, with a small but distinct ring on the stem. Contains amatoxins (same as death cap). Bolbitius titubans never has a ring and is bright yellow when fresh — but old, faded Bolbitius specimens could be confused with Conocybe if not carefully examined.
Side-by-Side Identification
| Trait | Yellow Fieldcap | Deadly Conocybe |
|---|---|---|
| Cap | 2–5 cm across. Ovoid to egg-shaped when very young, expanding to conical, then broadly bell-shaped, finally flattening with a tattered, upturned margin. Surface viscid to glutinous when fresh, smooth and glistening. Bright egg-yolk yellow when young, fading to pale ochre or buff from the margin inward. Strongly striate when expanded, with grooves extending nearly to the center. Flesh extremely thin and fragile, almost tissue-like. | 1-2.5 cm across. Conical to bell-shaped, sometimes flattening slightly with age. Tawny brown to ochre-brown, smooth, slightly sticky when moist. Hygrophanous, drying to a paler buff from the center outward. Surface often has fine radial striations when moist. |
| Gills | Narrowly attached (adnexed) to nearly free. Crowded. Pale yellow when young, becoming ochre-yellow, then cinnamon-brown as spores mature. Edges slightly fringed. Deliquescent — partially dissolving in wet weather, though far less dramatically than true ink caps. | Attached (adnate to adnexed), fairly crowded. Pale cinnamon-brown when young, darkening to rusty brown as spores mature. Thin and fragile. |
| Stem | 6–12 cm tall, 2–5 mm thick. Very slender, hollow, and extremely fragile — snaps with the lightest touch. White to pale yellow, covered with a fine white pruinose coating (powdery bloom) especially near the apex. Often slightly translucent. No ring. Base may have fine white mycelium. Tends to lean and eventually collapse. | 3-7 cm tall, 1-3 mm thick. Very slender and fragile, pale brownish, often with a thin, membranous ring (annulus) in the upper third. The ring is easily lost or collapsed against the stem. Base may be slightly enlarged. |
| Spore print | Rusty cinnamon-brown. | Rusty brown to cinnamon-brown. Always take a spore print on any small brown lawn mushroom before making any identification. |
| Odor | Not distinctive. Faintly mushroomy. | Mild, not distinctive. Some report a faintly earthy or mealy smell. |
| Habitat | Saprotrophic. Grows on well-rotted dung (horse, cow), composted straw, wood chip mulch, manured lawns, and nutrient-rich grassland. Also found on rotting hay bales, garden compost heaps, and occasionally in rich woodland leaf litter. Typically appears singly or in small, scattered groups. Prefers warm, wet conditions — often erupts overnight after summer rain. | Saprotrophic on decaying organic matter. Found in lawns, gardens, flower beds, wood chip mulch, compost, and disturbed grassy areas. Prefers moist, nutrient-rich soils. Common in suburban and urban settings. |
| Season | Late spring through autumn, typically May through October in the Northern Hemisphere. Peak fruiting in June through September during warm, rainy spells. Fruit bodies are extremely short-lived, often lasting only a single day. | Spring through autumn in temperate regions. Peak fruiting after warm rains in late spring and early fall. Can appear year-round in mild, wet climates. |
Found one of these in the wild? Don't rely on memory — identify it from a photo with Orangutany and check it against both species before you touch it.