Agaricus pequinii

🏷️ Description

Agaricus pequinii is a little-known but captivating edible mushroom from the Agaricaceae family. Though rarely encountered, it delights those lucky enough to find it with its firm texture, pleasant scent, and mild, agreeable flavor. 🌟 Named after the pharmacist Péquin, who discovered it in 1900, this species is a member of the Rubescentes group, section Bitorques.

🍽️ Culinary Status

Edible and of excellent quality, Agaricus pequinii is a treat for mushroom lovers. It has a dense, thick flesh that is white, sometimes turning faintly red when cut—especially near the upper stem. Its flavor is subtle but pleasant, and its aroma is mild and appealing.

🍄 Cap

• Size: 1.57 to 5.91 inches (4 to 15 cm) wide

• Shape: Initially convex or hemispherical, becoming flat or slightly depressed at the center with age

• Color & Texture: Whitish to creamy-ochre or light gray, often with membranous veil remnants or patches. Older specimens may show yellow-brown tones and cracking.

• Margin: Rolled inward when young, fibrous, later straightening and sometimes wavy or cracked.

🎨 Gills

• Attachment: Free from the stem

• Spacing: Dense and thin

• Color: Begin creamy-pink, transitioning through pink-brown, then dark brown to nearly black as the mushroom matures

• Sterile Edge: Lighter in color

📏 Stem

• Size: 3.93 to 4.72 inches (10 to 12 cm) high, 0.71 to 1.18 inches (1.8 to 3 cm) thick

• Shape: Central, cylindrical, initially short and bulbous, later elongating; base may taper into a spindle-like point

• Color & Features: Whitish, developing pressed grayish-burgundy scales below a distinctive low-set membranous corolla (resembling a pseudovolva), which often appears like a sheath at the base

• Flesh: Dense, white, with faint reddening along the upper stem when cut

🔬 Spores & Microscopy

• Spore Print: Dark brown to black

• Spores: Pale brown to dark, globose to elliptical, measuring 5–7.8 × 4.5–6.5 µm

• Cheilocystidia: Club-shaped to fusiform, 23–32 × 7–9 µm

🧪 Chemical Reactions

• No visible reaction when exposed to potassium hydroxide (KOH) or Schaeffer’s reagent.

🌍 Habitat & Distribution

• Found in Europe, and rarely observed

• Grows in diverse environments: 🏡 Greenhouses, 🐄 Barns, 🌳 Forests, 🏖️ Sandy dunes, and 🌱 Farmland

• Appears primarily in spring (but also in summer and autumn, especially June through October)

• Fruits in groups, sometimes in clusters

🧠 Key Identification Features

1. Pink gills when young, darkening with age

2. Low-set membranous corolla at the stem base

3. Flesh turns slightly red when cut

4. Pleasant aroma and mild flavor

5. Prefers cultivated or disturbed habitats, like gardens and greenhouses

🔍 Look-Alikes & Confusions

• Agaricus gennadii – smaller, larger spores (9–11 × 8–9 µm), and flesh does not redden

• Agaricus bitorquis – has a double ring

• Other similar species (but with different ecology or morphology):

  A. campestris, A. subperonatus, A. vaporarius, A. bresadolanus

📆 Fruiting Season

Primarily spring, but can also appear from June to October in warm climates. In Israel, it has been spotted in November to February, particularly near Jerusalem pines in Carmel Park.

📜 Synonyms

• Chitonia pequinii Boudier (1901), Bulletin de la Société mycologique de France, 17(1), p. 26 (Basionyme)

• Clarkeinda pequinii(Boudier) Saccardo & P. Sydow (1902), Sylloge fungorum omnium hucusque cognitorum, 16, p. 112

• Psalliota pequinii (Boudier) Jul. Schäffer (1932), Zeitschrift für pilzkunde, 11, p. 71

• Agaricus gennadii subsp.* microsporus Bohus (1975), Annales historico-naturales Musei nationalis hungarici, 67, p. 38

• Agaricus gennadii var. microsporus (Bohus) Wasser (1989), Tribe Agaricaceae Pat. of the Soviet Union, p. 100

Photo sources: Nicolas Schwab (CC BY 4.0)