Armillaria mellea, Armillaria
tabescens, Armillaria gallica
Common names: Honey Mushroom, Stumpy, Bootstrap Fungus.
Description: Armillaria species are commonly referred to as
“Honey Mushrooms” due to the yellow-brown color of their caps,
which are often sticky to the touch when moist. Honey
Mushrooms display a cespitose pattern of growth, where they
grow in dense clumps or tufts, with the stems of the individual
mushrooms, tapering and joining together at the base. Clumps
of Honey Mushrooms may contain up to 50 mushrooms, although
clusters of 10-20 are more common. Armillaria species fruit
primarily in the fall, although they may be seen in late summer
after heavy rains.
All species of Armillaria except A. tabescens have an annulus (i.e.
ring) around the stalk (see the top-left and middle-right photos
below). The annulus is the remnant of a veil that attaches from
the stem to the cap, but is torn away from the cap while
remaining attached around the stalk like a skirt as the mushroom
matures.
Caps of Armillaria species vary in size, ranging between 3-15 cm
on average when mature. They will sometimes have a few, tiny,
dark scales concentrated near the center-top of the cap, arranged
radially outward. The gills are attached or somewhat decurrent
(running slightly down the stem), and the spore print of this
mushroom is white. The stems can be tough and fibrous.
Ecology/Associated Habitat: Ecologically, Armillaria species
function as parasites of living hardwood trees (although they may
rarely be seen growing on conifers), where they cause an intensive
white-rot of their host. They also can function as saprotrophs and
are involved in the decomposition of dead hardwood logs, stumps
and roots (hence the common name, “stumpy”), recycling these
nutrients back into the environment. As a parasite, Armillaria
species can be invasive and devastating to a forest, moving tree to
tree via thick, black, cord-like structures called rhizomorphs, slowly
girdling an killing their tree hosts. After killing the trees, Armillaria
species may continue to live saptrophically on the remains of the
trees. Single Armillaria individuals have been shown to extend
miles across via mycelial network belowground, with ages
estimated at 1000s of years.
Poisonous look-alikes: Some Pholiota species, which also arise
in cespitose clusters from wood in the fall, may be mistaken for
Armillaria species at first glance, but are easily distinguished as
Pholiota species, which have a yellowish to greenish yellow cast
and a dark brown to grey-brown spore print (in contrast to the
white spore print of Armillaria species). Deadly Galerina species,
which can grow side-by-side Armillaria on wood, are easily
distinguished by their rusty-brown spore prints.
Armillaria species can also be mistaken for young, poisonous JackO-Lantern mushrooms (Omphalotus illudens) which may also grow
in cespitose groups at the base of hardwood trees, stumps or
buried roots. The Jack-O-Lantern can be distinguished from
Armillaria species by its dry, smooth, wavy-lobed orange to yelloworange cap and its yellowish spore print.
Tips on harvesting: Honey Mushrooms are best cut at the base
of the stipe with a sharp knife or scissors. Large scissors are good
for harvesting large, tightly-bound clusters. Since these
mushrooms often grow from the ground arising from buried roots
or next to hardwood stumps, it is a good idea to have a soft-bristled
brush (such as a small, unused, clean paint brush) handy to
remove excess dirt, sand or other debris before placing them in
your collection basket.
As with other mushrooms, younger buttons (before the caps flatten
out) are the most choice specimens for cooking. Older specimens
are also acceptable if firm and in good condition. The stems can be
fibrous and woody, but may still be used in soups and sauces if
peeled and minced.
Given their parasitic and saprotrophic ecology, Honey mushrooms
will kill and eat large trees, thus they appear in the same spot,
arising from the same substrates (e.g. trees, stumps, roots), year
after year. It is, therefore, advised to mark the position where you
found them growing (with a GPS if available) so that you may easily
return to the same spot in following seasons.
Possible allergic reactions and symptoms: A small percentage
of people may be sensitive to certain species of Armillaria. This can
be overcome by cooking them well, so we recommend you
thoroughly cook these mushrooms before serving. As with any
wild edible fungus, only try small amounts at first, do not try more
than one new species at a time.
Special considerations for storage: As with all other
mushrooms, store Honey Mushrooms in containers that allow the
diffusion of gas (such as paper or cloth bags). Never store any
portion of this or any other mushroom in an airtight container such
as a zip-lock bag
Photos:
Armillaria displaying cespitose grouping
Some morphological differences
Armillaria parasitizing living trees
Poisonous look-alikes
Pholiota aurivella
Omphalotus illudens
References:
Michael Kuo. Armillaria melea:
http://www.mushroomexpert.com/armillaria_mellea.html
Key to North American Armillaria species from Tom Volk
http://botit.botany.wisc.edu/toms_fungi/armkey.html#mellea
Tom Volk’s fungus of the month, April 2002
http://botit.botany.wisc.edu/toms_fungi/apr2002.html
Steve Brill
http://www.wildmanstevebrill.com/Mushrooms.Folder/Honey%20
Mushroom.html
Armillaria melea at Mycoweb:
http://www.mykoweb.com/CAF/species/Armillaria_mellea.html
Armillaria melea at Roger’s Mushrooms:
http://www.rogersmushrooms.com/gallery/DisplayBlock~bid~55
69.asp