Fauna
Fungus

Western Jack-o'-lantern

Omphalotus olivascens

Also known as Western Jack-O'-Lantern Mushroom

Western jack-o'-lantern mushrooms fruit in dense clusters around the bases of hardwood trees and submerged decaying roots along the Pacific coast. They feature olive-tinted orange caps and sharp, decurrent gills that emit a faint green bioluminescent glow in total darkness. As a saprobic fungus, this species plays an important role in breaking down dead oak and eucalyptus wood across its native range.

BioluminescentToxicFungus
Western Jack-o'-lantern reference1 / 7
(c) Nathan Wilson, some rights reserved (CC BY-SA) · cc-by-sa
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyDecaying Hardwood, Organic Matter
Predators
  • Fungus Gnats
  • Slugs
  • Beetles
ThreatsHabitat loss and removal of mature host trees
HabitatsOak woodlands, mixed hardwood forests, coastal valleys
Life spanFruiting bodies last 1–2 weeks; mycelium lives perennially
Classification
  1. FamilyOmphalotaceae
  2. SpeciesOmphalotus olivascens
Range & activity
Range data is not available yet.
Safe observation
Interaction riskHigh
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is high
Contains severe gastrointestinal toxins and has look-alikes; never eat wild fungi based on app identification alone.
Why it is dangerous
Contains illudin toxins that induce severe vomiting, stomach cramps, and extreme nausea within hours of ingestion.
How to recognize a risky encounter
Recognized by dense clumping growth at tree bases, olive-orange caps, and deep decurrent gills.
What to do
Do not harvest or consume; admire and photograph from a safe distance.
Responsible observation
  • Nighttime Viewing: Observe fresh clusters in absolute darkness to spot faint green gill glow.
  • Safe Identification: Examine the true decurrent gills running down the stem to distinguish from chanterelles.
  • Leave in Place: Photograph mushrooms where they grow without disturbing the substrate.
Related species
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