mushroom club of georgia

Mushroom Club of Georgia

mushroom club of georgia

Mushroom Club of Georgia

Mushroom of the Month: September 2025, Armillaria (Honey Mushrooms)

by | Sep 25, 2025 | Mushroom Of The Month

Cluster of yellow mushrooms growing on a decaying log in a forest, with fallen leaves and pine needles on the ground. A person’s leg is visible in the background.
 

Clusters of yellow-capped mushrooms grow at the base of a tree in a forest, surrounded by fallen leaves and green plants.

honey mushroom shot by Inaturalist user @fungee

When golden clusters of mushrooms erupt around tree bases in late summer, they aren’t just a pretty sight, they’re a sign of Armillaria at work. Known collectively as honey mushrooms, these fungi form tight bunches of caps and stems that fuse at their base. The genus includes several species (most notably Armillaria mellea and A. tabescens) that are both feared and celebrated: feared by arborists because of the damage they cause to host trees, and celebrated by foragers for their firm texture and nutty flavour. Armillaria spreads underground via black, shoestring‑like rhizomorphs that can extend many feet, connecting entire groves in a subterranean web

Common Names: honey fungus, honey mushroom, stump mushroom, stumpie, pipinky or pinky
Family: Physalacriaceae
Genus: Armillaria
Season: Late summer through autumn (August–November)
Habitat: Dense clusters at the bases of living or dead trees, stumps and buried roots; parasitic or saprobic on hardwoods and sometimes conifers.

(Arllimaria)Taxonomy & Nomenclature

  • First Described: The name Armillaria was defined in 1821 byElias Magnus Fries, but at that time most gilled mushrooms were considered to belong to the genus Agaricus and Armillaria was only a subgenus (a “tribe”).  In 1857, Friedrich Staude established the independent genus.

  • Current Genus Name: Armillaria species morphologically similar to A. mallea were not effectively distinguished until the development of “biological species” defined as intersterile groups by Veikko Hintikka in 1973.

  • Modern Tazomony: Early mycologists lumped hundreds of honey‑coloured mushrooms into A. mellea. DNA and mating studies later split the complex into about a dozen species mushroom-appreciation.com, and today the genus Armillaria is much smaller; species still share similar ecology and visible black rhizomorphs

  • Etymology:

    • Armillaria is derived from the Latin armilla (“bracelet”), alluding to the distinct ring (annulus) around the stem of many species.

    • The epithet mellea(most common honey mushroom) means “honey‑coloured,” referring to the cap’s golden hue.

Did You Know?
Some Armillaria colonies are among the world’s largest and oldest organisms. A single Armillaria mycelium nicknamed the “humongous fungus” in Oregon spans more than 3.4 square miles and is estimated to be over 2,500 years old.

 

(Arllimaria)Morphology & Quick ID Guide

Shape: Cap 2.5-10 cm; convex, becoming broadly convex to more or less flat. Thick stipe tapering to base.
Color: Caps range from honey‑yellow to reddish‑brown, sometimes with tiny dark hairy scales near the centre. Gills begin whitish to pale cream and may develop pinkish or rusty spots with age
Texture: Cap surfaces are sticky when wet; flesh is white and firm. Gills are covered by a pale yellow veil that becomes a ring on the stem as the mushroom matures.
Stipe: Stems are stout (2–6 inches long), fibrous, and often fused together at the  They start pale and darken from flesh‑colored to brown; most species have a prominent whitish ring around the upper stem. The ringless honey mushroom (A. tabescens) lacks this annulus
Spore Print: White; spores are smooth, elliptical and colourless
Microscopic: Spores typically measure 7–9 × 6–7 μm; basidia lack basal clamps in A. mellea. Rhizomorphs are black, shoestring‑like cords that bundle mycelial threads and can glow faintly (foxfire) when actively growing.

Microscopic view of oval-shaped fungal spores with a measuring scale beneath them; image credit: Michael Kuo.

Armillaria mellea_ Spore Print_ Michael Kuo_MushroomExpert

 

Did You Know?
The common name shoestring root rot comes from the honey mushroom rhizomorphs: their appearance resembles black shoestrings wrapped around roots and stems.

 

Close-up of tree bark with dark, irregular lines and patterns created by insect activity or fungal growth on the wood surface.

honey mushroom rizomorph shot by Inaturalist user @steve_mcwilliam

A long, thin, tangled piece of brown plant material rests on a white surface, with some small spots and grass visible at the edge.

honey mushroom rizomorph shot by Sam Landes

Allamaria Rizomorphs: the hidden networks

A defining feature of honey mushrooms is their ability to spread underground and aboveground via black, shoestring‑like cords called rhizomorphs. Unlike the delicate, threadlike mycelium that permeates soil and wood, rhizomorphs bundle these threads into flexible strands that can run through soil and beneath bark. They are dark reddish‑brown to black and can range from a few inches to many feet long. When a cluster of honey mushrooms appears at a tree base, you can often trace the fruiting bodies back to these long, tough cords weaving through the roots and soil.

  • Structure & Function: Rhizomorphs act as an underground/aboveground highway, allowing Armillaria to move water, nutrients and even toxins from one host to another. They connect diseased trees with healthy neighbors, facilitating infection and nutrient transfer. As they grow, rhizomorphs branch and fuse, forming a subterranean network that can girdle roots and kill trees over time.

  • Growth Rate: These cords can expand about 2–4 feet per year, and under favorable conditions individual rhizomorphs may stretch up to 30 feet (9 m) and 1/4 inches (5mm) in length to reach a new host. By using rhizomorphs rather than dispersing spores alone, Armillaria ensures that new infections start with a robust nutrient source.

(Allmaria) Ecology & Habitat

  • Lifestyle: Armillaria species are both parasitic and saprotrophic. They cause white rot in living trees and continue feeding on the dead wood, recycling nutrients in forest ecosystems.

  • Growth Pattern: They fruit in dense, cespitose clusters; stems fuse at the base and can number dozens in a cluster.

  • Seasonality: Honey mushrooms fruit primarily from late summer through fall, typically after heavy rains; in warmer climates they may appear nearly year‑round.

  • Ecological Role: The fungi spread through thick, black rhizomorphs that run through soil and under bark, allowing them to move from tree to tree. These rhizomorphs can grow up to thirty feet long per year, girdling roots and causing Armillaria root rot—a major cause of hardwood tree death.

 

 

A group of people stands outdoors around a table with natural specimens as an older man gestures and explains, holding a branch.

MCG walk 9-10-25 MCG Treaseurer Sam Landes sharing about the Honey Mushrooms Rizomorphs 2

A cluster of brown-capped mushrooms grows from the forest floor amid fallen leaves and moss, with trees and autumn foliage in the background.

honey mushroom shot by Inaturalist user @mandiequark

(Allmaraia) Geographic Distribution

  • Worldwide Range: Honey mushrooms occur throughout the temperate regions of the Northern Hemisphere. Armillaria mellea is found across North America, Europe and northern Asia and has been introduced to South Africa.

  • North America: They are widespread east of the Rockies, from the Gulf Coast to southern Canada, and some species extend into California.

  • Habitat Preferences: Armillaria species inhabit forests, gardens, orchards and vineyards, preferring moist soils but tolerating a wide range of conditions.

 

Clusters of brown mushrooms grow at the base of a tree trunk, surrounded by green leafy plants and soil.

Ringless Honey Mushroom captured at MCG walk 8-30-25

A close-up view of an orange-brown mushroom growing among moss and grass on a forest floor.

honey mushroom shot by mcg member Darling Ngoh

Edibility & Uses

  • Edibility: Honey mushrooms are edible when young and thoroughly cooked, but some individuals experience gastrointestinal upset . Always cook them well and sample only a small amount the first time.

  • Culinary Notes: These mushrooms are firm and meaty; sautéing or blanching improves their flavour and removes any bitterness. Drying concentrates their taste and extends shelf life.

  • Caution: Never eat raw honey mushrooms, and be certain of the identification to avoid confusion with toxic look‑alikes such as deadly Galerina species.

 

A close-up view of clustered light brown mushrooms growing on a mossy tree trunk, showing their smooth, rounded caps with fine speckles.

honey mushroom shot by Inaturalist user @bacres

 

(Armillaria) Observing & Photographing Tips

  • Where to Look: Search around the bases of oaks, maples, cherries and other hardwoods in late summer and autumn; honey mushrooms always originate from buried wood or roots.

  • Cluster Clues: When collecting, expect to harvest an entire clump; stems are fused at the base. Remember that ringless species fruit earlier in the season.

  • Photography: Capture the honey‑coloured cap and the distinctive ring by gently lifting one cap to reveal the gills. Macro lenses highlight the tiny scales and texture.

  • Community Science: Upload observations to iNaturalist to help track Armillaria species distribution and rhizomorph impacts on local forests.

 

A group of people stands around a table outdoors, observing various mushrooms and fungi samples as an instructor explains and gestures with one hand raised.

MCG walk 9-10-25 MCG Treasurer Sam Landes sharing about the Honey Mushroom Rizomorphs.

Join an MCG Foray!

Curious to see honey mushrooms and their rhizomorphs in person?
Visit the Event Calendar and Register for our upcoming Forays » to explore fungal wonders with the Mushroom Club of Georgia; learn field ID tips, meet fellow members, and help map exotic and native speycies across the state!

References: