Omphalotus olivascens
🏷️ Description
Meet Omphalotus olivascens (aka western jack-o'-lantern mushroom), the bewitching but toxic mushroom of the California Floristic Province! 🍂🧡 Often mistaken for delicious chanterelles, this glowing fungus hides a dark secret—its compounds can cause intense cramps, vomiting, and diarrhea if consumed. The culprit? Illudin S, a potent sesquiterpene unique to the Omphalotus genus. 😵💀
First identified as a distinct species in 1976, this fungal trickster has subtle olive overtones that set it apart from its European relatives. A rare blue-fleshed variety (O. olivascens var. indigo) has even been spotted in Baja California! 🌊💙
But it's not all danger—this mushroom boasts powerful antimicrobial properties, showing promise against bacteria like E. coli and Salmonella. 🦠🔬 Plus, for the creative souls, it serves as a natural dye, shifting from purple to red-brown over time. 🎨🧶
A mesmerizing blend of toxicity, utility, and mystery, Omphalotus olivascens is a reminder that nature's most enchanting wonders often come with a warning! ⚠️🍄💡
🔎 Identification
This glowing trickster of the fungal world may look like a chanterelle, but don’t be fooled! ⚠️ Unlike true chanterelles, Omphalotus olivascens has blade-like gills, olive tones, and a bioluminescent glow when fresh. It thrives on wood, often appearing in large clusters at the base of oaks and eucalyptus trees.
🧢 Cap: 1.97 to 7.87 inches (5 to 20 cm) wide, convex when young, becoming flat or vase-shaped. Smooth, moist, dull orange to orange-brown with olive discolorations as it matures.
🌿 Gills: Deep, true gills that run down the stem (decurrent), yellowish olive when young, turning yellow to orange. Glows in the dark! ✨
📏 Stem: 1.97 to 5.91 inches (5 to 15 cm) long, 0.39 to 1.57 inches (1 to 4 cm) thick, smooth, tapering at the base, yellowish-olive with brown stains.
🧡 Flesh: Pale orange to pale olive, unchanging when sliced.
👃👅 Odor & Taste: Mild, not distinctive. Do not taste—it's poisonous!
🎨 Spore Print: White to pale yellow.
🏡 Habitat & Season:
Saprobic (feeds on decaying wood), growing in dense clusters on hardwood stumps or buried roots.
Prefers oaks and eucalyptus.
Found in California and Baja California from late fall to mid-winter.
🔬 Microscopic Features:
Spores globose to ovoid (6.5–8 × 6–6.5 µm), smooth, nonamyloid.
Spore print: Cream to pale yellow.
Basidia: Clavate, 4-sterigmate (35–38 × 4–6 µm).
Pileipellis: A cutis with slightly roughened elements.
👀 Look-Alikes
Several mushrooms resemble Omphalotus olivascens, but beware—many are also toxic and bioluminescent! 🌿⚠️
1️⃣ Omphalotus olearius – Found in eastern North America, this species shares the same glowing green trait and toxic properties.
2️⃣ Omphalotus japonicus – Native to Japan and eastern Asia, this bioluminescent mushroom was formerly classified under Lampteromyces japonicus.
3️⃣ Omphalotus nidiformis – Found in Australia, this eerie mushroom is O. olivascens' closest relative, with a nearly identical glow-in-the-dark effect.
4️⃣ Gymnopilus junonius – Similar in appearance, but not bioluminescent. While it's sometimes mistaken for Omphalotus, it has different chemical properties.
💡 Tip: Omphalotus olivascens glows best when fresh! To see its greenish bioluminescence, sit in a completely dark room for several minutes—sometimes, the glow is bright enough to read a newspaper!
Photo sources:
Photo 1 - Author: Garth Harwood (CC BY-SA 4.0)
Photo 2 - Author: Alexander Wentworth (CC BY 4.0)
Photo 3 - Author: Alex (CC BY 4.0)
Photo 4 - Author: Jason Schock (CC BY 4.0)
