• Proposed
  • Under Assessment
  • Preliminary Assessed
  • Assessed
  • ENPublished

Hygrocybe flavifolia (A.H. Sm. & Hesler) Singer

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Scientific name
Hygrocybe flavifolia
(A.H. Sm. & Hesler) Singer
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
IUCN Red List Category
EN C2a(i)
Proposed by
Else Vellinga
Else Vellinga
Christian Schwarz
Tommy Knutsson, Else Vellinga
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Syn. Hygrophorus flavifolius A.H. Sm. & Hesler

Why suggested for a Global Red List Assessment?

A rare wax cap species only occurring in mature coastal forests of California (USA), and fruiting very irregularly. It is exemplary for the specific redwood (Sequoia sempervirens) forest mycoflora that consists of many Hygrocybe and Entoloma subg. Leptonia species.

Evaluation Ekenäs april 2015: Endangered under criterion C2a(i) as the number of estimated localities is definitely not more than 125 and population estimate much below 2.500 mature individuals together with ongoing habitat loss due to forest harvesting for timber.

Geographic range

Coastal northern California, recorded from Orrick in the north to Santa Cruz as the most southern occurrence.

Population and Trends

Since the collection of the type collection at the end of November 1937 in Northern California (Humboldt County), it took till 1994 for a second collection (in Marin County) , after that, another 16 years for reports of this species from several counties (Marin, Santa Cruz, Contra Costa). In the last few years, it has repeatedly been recorded, all from central coastal California.

Population Trend:

Habitat and Ecology

Terrestrial in Coastal Redwood forest (Sequoia sempervirens), and occasionally under Bay Laurel (Umbellularia californica) on bare soil. Nutritional mode not known.


The coastal redwoods, Sequoia sempervirens, only occur from southernmost coastal Oregon southwards to Big Sur in California. These trees depend on summer fogs and winter rains. Due to climate change, the fog patterns have considerably changed during the last 100 years with a significant decrease of the extent of the fog in summer (Johnstone & Dawson, 2010), and winter rains have been coming much less reliably during the last 10 years than before.
Coastal redwood forests have been extensively logged for timber and logging is ongoing, resulting in patchiness of available habitat.
Furthermore, in the northern part of the range, the forest understory vegetation has changed during the last 30 years, with an increase of Polystichum, and a decrease of more open forest floor, resulting in the disappearance of many characteristic fungal species.
Habitat destruction is also a threat; one of the known sites of this species is on the campus of the University of California at Santa Cruz.

Conservation Actions

Protect the habitat, in other words, no logging in coastal redwood forests.
Curb carbon emissions, and reverse the warming trend of the global climate.

Research needed

Use and Trade


Johnstone JA, Dawson TE, 2010. Climatic context and ecological implications of summer fog decline in the coast redwood region. PNAS 107: 4533–4538.

Largent DL, 1985. The Agaricales (gilled fungi) of California. 5. Hygrophoraceae.

Noss RF (ed.) 2000. The Redwood Forest: History, Ecology, and Conservation of the Coast Redwoods. 339 pp.

Smith AH, Hesler LR, 1942. Studies in North American species of Hygrophorus - II. Lloydia. 5: 1–94.

Known distribution - countries

Regional Population and Trends

Country Trend Redlisted