Bulbous Honey Fungus

not listed

NNR - Unranked

not listed

Bulbous Honey Fungus is a common, late season, gilled mushroom. It occurs in Europe, Asia, and North America. In the United States it occurs east of the Great Plains and in the west from Washington to central California west of the Rocky Mountains. It also occurs across southern Canada and in central Mexico. It appears in late summer and fall, alone, in groups (gregarious), or is loose small clusters. It is found most often growing on the ground attached to underground roots, but it is also found on stumps and logs and on the base of living trees. It grows usually on hardwoods but also occasionally of conifers. It usually obtains its nutrients from dead wood (saprobic) but can also attack living trees weakened by disease.

When it first appears the cap is convex and pinkish-brown or brownish-yellow. The upper surface may be dry or sticky. It is hairless but is covered with slender, erect or upward sloped fibers (fibrils). The gills are covered with a white, cottony, layer of tissue (partial veil) extending from the margins of the cap to the stalk. As it ages the cap expands, becoming broadly convex to almost flat. Shreds of tissue, remnants of the partial veil, hang from the margin. As it dries out it fades considerably toward the edges while remaining dark in the center. Mature caps are 1″ to 3¾″ (2.5 to 9.5 cm) in diameter. The margins are lined.

The gills are whitish, closely spaced, and broadly attached to the stalk (adnate), sometimes slightly running down the stalk (decurrent). As they age they turn pale orange and develop rust-colored spots. They turn pinkish to brownish when bruised. Between the main gills there are two or three series of short gills that do not extend to the stalk.

The stalk is 1½″ to 4″ (4 to 10 cm) long and ¼″to 11⁄16″ (6 to 18 mm) thick. It is swollen at the base, appearing club-shaped. There is a flimsy ring of tissue, the remains of the partial veil, on the upper part of the stalk. Sometimes there is no ring just a yellowish ring zone. The stalk is whitish or pale pink, becoming grayish-brown on the lower half with age.

The flesh is whitish. It does not change color when sliced. It is edible when cooked and has a mild to bitter taste.

The spore print is white.

The underground vegetative portion (mycelium) of this mushroom is often very extensive, sometimes covering several acres. Curiously, the mycelium is bioluminescent but the fruiting body (mushroom) is not. The purpose of the bioluminescence may be to attract insects that will disperse the spores, or to deter insects and animals that may eat it. It could also be a byproduct of other biochemical functions and have no other purpose.

Hardwood and sometimes conifers

Late summer and fall.

In the early 1990s a huge underground mycelium of Armillaria gallica was found covering 37 acres in the Upper Peninsula of Michigan. Molecular genetics showed the mycelium to be about 1,500 years old. It came to be known as the “Humongous Fungus”, became a popular tourist attraction, and spawned a annual fungus festival. At the time of its discovery it was thought to be the largest organism on earth, a title formerly held by Pando, the quaking aspen grove in Utah. Since that time, three other organisms have held that title. The current (2022) holder is the marine plant Posidonia australis in Shark Bay, Australia.

Sources

4, 24, 26, 29, 30, 77.

Common

Species Group
Armillaria gallica is one of nine North American species that are similar in appearance and difficult to distinguish. They are often treated together as the cryptic species complex Armillaria mellea group. Five or six of them occur in Minnesota.

Species
This species was formerly called Armillaria bulbosa. In 1987 it was determined that the species name was misapplied, and the species was given the new name Armillaria gallica.

Location: Hennepin County