Mycena flavoalba

Description

Mycena flavoalba is an inedible mushroom species in the family Mycenaceae. The cap is initially conical in shape, before becoming convex and then flattening out. The cap color is ivory-white to yellowish-white, sometimes more yellowish at the center. It is common in Europe, the Middle East, and North America, where it grows scattered or in dense groups under conifers and on humus in oak woods.

Although generally rare, the species sometimes occurs in large quantities in certain localities. In the United States, it has been collected from Colorado, Idaho, Michigan, North Carolina, Oregon, Washington, Wyoming, Florida, and Kansas. It is also listed as "Least Concern" in the Danish Red Data Book.

Common names: Ivory Bonnet, Bleekgele mycena (Netherlands), Helmovka žlutobílá (Czech Republic), Weißgelber Helmling (German).

Mushroom Identification

1. Cap

   0.5–2 cm in diameter, initially convex or cone-shaped, later convex-spread, convex-bell-shaped, spread, with a small tubercle in the middle, with a thin, slightly toothed, translucent edge. The surface is hygrophanous, smooth, bare, streaked, whitish-yellowish, creamy-yellowish, lemon-yellow, yellow, darker and brighter in the middle, lighter near the edges, whitish, almost white with age.

2. Gills

   The hymenophore is lamellar. The gills are thin, narrowly attached, and white.

3. Stem

   The stem is 2-6 cm high, 0.1-0.2 cm in diameter, cylindrical, smooth, hard, hollow, translucent, floury above, glabrous below, white, yellowish-white, with white pubescence at the base.

4. Flesh

   The flesh is thin, translucent, white, reddens slightly when cut, tasteless, with a pleasant smell.

5. Spores

   6-9 * 3-4 μm, elliptical in shape, with a smooth surface.

6. Spore Print

   White or pale yellow.

7. Habitat

   Grows from the beginning of summer to the end of autumn, in deciduous and coniferous forests, in gardens and parks, on meadows and pastures, on roadsides, on deciduous and coniferous litter, among grass, among moss, in large groups.

8. Microscopic Features

   The basidia (spore-bearing cells) are four-spored. The pleurocystidia and cheilocystidia (cystidia found on the face and edge of a gill, respectively) are similar in structure and abundant, ventricose with long, rather narrow necks, and measure 46–62 by 9–14 μm. The neck is often encrusted with a mucilaginous substance, but it is otherwise smooth and hyaline. The flesh of the gill is homogeneous, and stains pale yellow in iodine. The flesh of the cap has a thin, poorly differentiated pellicle (a thin membrane), a somewhat differentiated hypoderm (that is most pronounced in old caps) and the remainder is made up of somewhat enlarged cells that stain pale yellow in iodine.

Look-Alikes

1. Hemimycena lactea and Hemimycena delectabilis

   It can be distinguished from these species by its white to the yellowish cap, and differences in the shape of both its spores and caulocystidia (cystidia on the stem).

2. Hemimycena conidiogena

   A Spanish species described in 2005, is also similar in appearance, but differs in the distribution of pigment in the cap, and the differential staining in response to the dye cresyl blue — M. flavoalba is positive, while H. conidiogena is negative.

History

First described as Agaricus flavoalbus by Swedish mycologist Elias Magnus Fries in 1838, it was assigned its current name in 1872 by Lucien Quélet.

American mycologist Rolf Singer transferred the species to the genera Hemimycena and Marasmiellus in 1938 and 1951, respectively. Singer later changed his mind about these placements, and his 1986 Agaricales in Modern Taxonomy, he considered the species a Mycena.

The specific epithet flavoalba ("yellow-white") is a compound of the Latin adjectives flavus ("yellow) and alba ("white").

Synonyms

1. Hemimycena flavoalba (Fr.) Singer, 1938

2. Agaricus flavoalbus Fr.

3. Agaricus luteoalbus Bolton

4. Hemimycena flavoalba (Fr.) Singer

5. Marasmiellus flavoalbus (Fr.) Singer, 1951

6. Mycena argillascens Mitchel & A.H. Sm.

7. Mycena lineata ss. J. Schröt.

8. Mycena luteoalba (Bolton) Gray

Photo sources:

Photo 1 - Author: James Lindsey (CC BY-SA 2.5)

Photo 2 - Author: Björn S... (CC BY-SA 2.0)

Photo 3 - Author: James Lindsey (CC BY-SA 2.5)

Photo 4 - Author: Björn S... (CC BY-SA 2.0)

Photo 5 - Author: Toffel (CC BY-SA 3.0, 2.5 Generic, 2.0 Generic and 1.0 Generic)