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Fused Collybiopsis (Collybiopsis confluens)

Collybiopsis confluens
Current name

Index Fungorum    Collybiopsis confluens (Pers.) R.H. Petersen
MycoBank    Collybiopsis confluens (Pers.) R.H. Petersen
 

Other names

Fused Marasmiellus, fused Marasmius, merging "penny mushroom", fused Collybia, confluent Collybia, fused Gymnopus.

Systematic position
Specific epithet etymology

cōnfluens — 1) flowing together, merging; 2) мик. confluent, fused. Pres. act. participle of cōnfluo, flūxī, -, ere — 1) to flow together, to merge; 2) to flock together, to gather in masses, to converge.

Synonyms

Collybia confluens (Pers.) P. Kumm., Der Führer in die Pilzkunde: 117 (1871) 

Marasmius confluens (Pers.) P. Karst., Bidrag till Kännedom av Finlands Natur och Folk 48: 102 (1889)

Gymnopus confluens (Pers.) Antonín, Halling & Noordel., Mycotaxon 63: 364 (1997) 

Gymnopus confluens subsp. confluens (Pers.) Antonín, Halling & Noordel., Mycotaxon 63: 364 (1997)

Gymnopus confluens var. confluens (Pers.) Antonín, Halling & Noordel., Mycotaxon 63: 364 (1997) 

Marasmiellus confluens (Pers.) J.S. Oliveira, Mycological Progress 18 (5): 734 (2019) 

Vestipedipilus confluens (Pers.) J.J. Hu, B. Zhang & Yu Li, Mycosphere 15 (1): 454 (2024) 

General description

The sheer number of names makes it clear that this mushroom has been tossed around between genera and families like a louse in a bathhouse.

Habit
Fruiting body
Agaricoid (cap and stipe)
Hymenophore
Lamellate (gills present, including folded or rudimentary)
Fruiting period (list)
May (21st–31st)JunJune (1st–10th)June (11th–20th)June (21st–30th)JulJuly (1st–10th)July (11th–20th)July (21st–31st)AugAugust (1st–10th)August (11th–20th)August (21st–31st)SepSeptember (1st–10th)September (11th–20th)September (21st–30th)
Mushroom cap

2–6 cm in diameter; initially hemispherical to convex, then broadly conical, later convex-spreading with a blunt umbo, sometimes depressed; surface smooth, with a thin, wavy, incurved margin; ochre-brown to reddish-brown with a lighter margin, fading to pale or creamy.
Gills very crowded, narrow, with finely serrated edges, adnate at first, then free or emarginate; whitish to yellowish.

Stem

4–10 cm long and 0.2–0.5 cm in diameter; cylindrical, often flattened, longitudinally striate-furrowed, dense, hollow inside; initially whitish to yellowish-brown, darker toward the base, then reddish-brown to red-brown, later sometimes blackish-brown; matte, with a "white bloom" of fine whitish hairs along its entire length, white-pubescent at the base.

Flesh

Thin, watery, dense; in the stipe tough and fibrous; taste indistinct.

Odor

Weak, indistinct.

Microscopy

Spore print white. Spores broadly ellipsoid, often slightly ovoid.

Ecology and distribution

A xylotroph; found in coniferous and mixed forests with spruce (Picea), on forest litter, on wood buried in or near the soil, in groups or small clusters, sometimes with fused stipes; common. Widespread.

Fruiting

June–September

Nutritional properties
Inedible

Of no culinary value due to its fibrous flesh and small size.

Similar species

Water Gymnopus (Gymnopus aquosus) — distinguished by paler coloration and habitat. Fairy Ring Mushroom (Marasmius oreades) — distinguished by habitat.

Link to this page for printed editions
Shipovalov A.G. Fused Collybiopsis (Collybiopsis confluens) - Mushrooms of Vologda Region [Electronic resource] URL: https://xn----7sbancweblffgklubds60aja.xn--p1ai/en/fused-collybiopsis-collybiopsis-confluens (accessed: 13.04.2026).
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