What You Should Know
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.
Other names: Wrinkled Fieldcap, Året agerhat (Danish).
Agrocybe rivulosa Mushroom Identification
3 to 11 cm wide, hemispherical to broadly convex or flat; shallow ochre surfaces develop radial folds connected by a network of intersecting veins.
Adnateinitially cream-gray, gray-brown as spore maturity increases.
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.
Oval, smooth, 11.5-12 x 7-8 µm; with prominent germ hole.
Odor and Taste
Saprobic, in large groups or in blocks on sawdust piles and deep-covered flower beds.
April to November.
Agrocybe rivulosa Look-Alikes
Grows in spring and early summer on wood chip mulch. It's usually smaller and has a darker cap.
Has darker lamellae and spores.
Agrocybe rivulosa Taxonomy and Etymology
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 1 - Author: Lukas from London, England (Creative Commons Attribution-Share Alike 2.0 Generic)
Photo 2 - Author: Thomas Pruß (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 3 - Author: Rob Hille (Creative Commons Attribution-Share Alike 3.0 Unported)
Photo 4 - Author: Rob Hille (Creative Commons Attribution-Share Alike 3.0 Unported)