Agaricus osecanus

Description

Agaricus osecanus is an edible white to slightly brown mushroom. The flesh is white and the smell is pleasant, sweetish, variously described as aniseed, almond or mushroom. Grows in mainland European countries and eastern parts of North America.

The cap surface turns lemon yellow when a dop of KOH solution is applied. This is a characteristic of Agaricus species in the Arvenses, Minores and Xanthodermati groups.

Common names: White-capped Mushroom.

Mushroom Identification

1. Cap

   The cap is 5-15 cm in diameter, thick-fleshed, initially hemispherical, with an upturned edge, later convex-spread, sometimes concave or flattened in the middle, with a spread, wavy, cracked edge. The surface of the cap is glabrous, silky-fibrous, sometimes cracked-scaly in the center, flaky near the edge when mature, white, snow-white, sometimes grayish-yellowish-white, yellowing with age, with remnants of the cover on the edge.

2. Gills

   Thick, thin, free, initially light, light reddish, later dark brown, with a light, sterile edge.

3. Stem

   The stem is 6-10 cm high, 1.5-5 cm in diameter, cylindrical, smooth, slightly narrowed to the base, often fusiform, at first solid, later hollow, with a ring, silky-fibrous, at first rough, later bare, white. Sometimes stem has a yellow spots below the ring and it is often covered with round flaky granules that turns yellow in places of contact. The ring is simple, wide, later hanging, white, smooth, the edge is covered with a white, later yellowish, flaky coating, located in the upper part of the leg.

4. Flesh

   The flesh is white, sometimes with yellow spots. On the cut it acquires a yellowish color, especially in the stem, tasteless, with the smell of almonds.

5. Spores

   5-8 * 4-5.5 μm, broadly ovoid, with a smooth surface, with one fluorescent droplet, light brown.

6. Spore Print

   Dark brown.

7. Odor and Taste

   The odor is faint and reminds crushed almonds. The taste is mild mushroomy.

8. Habitat

   It is saprobic and occurs in permanent pastures and parkland and on grassy roadside verges.

9. Season

   July to October.

Look-Alikes

1. Agaricus arvensis

   Have a similar white cap but turned to a more yellow hue as it matured.

2. Agaricus xanthodermus

   Similar but with a flat central area instead of the dome of A. osecanus.

History

In 1951 the Czech mycologist Albert Pilát (1903-1974) scientifically described this species and gave a binomial scientific name Agaricus osecanus.

The Latin adjective canus means white, and the prefix os- (possibly appended with an "e" for pronunciation) means bone. So it seems likely that osecanus means "white as a bone" or "bone white", since this is actually the base color of the mushroom.

Synonyms

1. Psalliota nivescens F.H. Møller, 1952

2. Psalliota nivescens var. parkensis F.H. Møller, 1952

3. Agaricus nivescens (F.H. Møller) F.H. Møller, 1952

Photo sources:

Photo 1 - Author: Bryant Olsen (Attribution-NonCommercial 2.0 Generic)