Agrocybe rivulosa

Description

Agrocybe rivulosa is rare a species of mushroom in the genus Agrocybe. It is a relatively large mushroom, with a stem of 5 to 10 cm, and a cap that reaches 4 to 10 cm across. The color of the cap ranges from yellow to pale orange-brown. It grows tall with a whitish fleshy stem. It has been eaten and is reasonably tasty with no obvious toxicity.

Some field guides list this fungus in the Bolbitiaceae family.

Common names: Wrinkled Fieldcap, Året agerhat (Danish).

Mushroom Identification

1. Cap

   3 to 11 cm wide, hemispherical to broadly convex or flat; shallow ochre surfaces develop radial folds connected by a network of intersecting veins.

2. Gills

   Adnateinitially cream-gray, gray-brown as spore maturity increases.

3. Stem

   5 to 10 cm long, 1 to 1.5 cm in diameter; hollow; tapering slightly towards tip; white, creamy ochre with age; persistent, thinly hanging stem rings.

4. Spores

   Oval, smooth, 11.5-12 x 7-8 µm; with prominent germ hole.

5. Spore Print

   Brown.

6. Odor and Taste

   Not distinctive.

7. Habitat

   Saprobic, in large groups or in blocks on sawdust piles and deep-covered flower beds.

8. Season

   April to November.

Look-Alikes

1. Agrocybe praecox

   Grows in spring and early summer on wood chip mulch. It's usually smaller and has a darker cap.

2. Leratiomyces percevallii

   Has darker lamellae and spores.

History

In 2003 Dutch mycologist Marijke M. Nauta described this species and published it in Persoonia.

The generic name Agrocybe is derived from Agro-, of fields, and -cybe, head or cap.

The specific epithet rivulosa refers to the wrinkled groove that descends like a creek from the center of the cap.

Photo sources:

Photo 1 - Author: Lukas from London, England (CC BY-SA 2.0)

Photo 2 - Author: Thomas Pruß (CC BY-SA 3.0)

Photo 3 - Author: Rob Hille (CC BY-SA 3.0)

Photo 4 - Author: Rob Hille (CC BY-SA 3.0)