Cystoderma jasonis (Cooke & Massee) Harmaja - Pine Powdercap

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Agaricaceae

Cystoderma jasonis - Pine Powdercap

These colourful little mushrooms look rather like dark specimens of the Earthy Powdercap, which are most commonly seen in mossy grassland habitats. The lower stem is covered with large granules, while the smooth upper stem is often (as here) flushed purple.

Cystoderma amianthinum - Earthy Powdercaps growing on in a fairy ring


Uncommon but far from a rare find in Britain, this mainly woodland mushroom occurs in sites scattered across England, Wales, Ireland and scotland, but it is most common in the conifer plantations and forests of central Scotland. The Pine Powdercap is also recorded from other countries on mainland northern Europe and from parts of North America.

Taxonomic history

When British mycologists Mordecai Cooke and George Edward Massee (1850 - 1917) described this species in 1888, they gave it the scientific name Agaricus jasonis. In 1978 the Finnish mycologist Harri Harmaja (b.1944) transferred the Pine Powdercap to the genus Cystoderma, creating its currently accepted scientific name Cystoderma jasonis.

Synonyms of Cystoderma jasonis include Agaricus jasonis Cooke & Massee, Armillaria jasonis (Cooke & Massee) Sacc., and Cystoderma amianthinum var. longisporum Kühner.


Powdercaps usually do have granular cap surfaces - the generic name Cystoderma means 'blistered skin' - but their most distinctive feature is the marked contrast between the smoothness of the stem above the ring and its scaly surface below. The overall impression is of a mushroom wearing an ill-fitting stocking.

The specific epithet jasonis may perhaps be in some way a reference to the mythical ancient Greek hero Jason, who led the argonauts in a quest to seize the golden fleece (which perhaps represents the golden cap and lower stems cales of this mushroom)... but maybe it's not.Who knows? Any other suggestions?

Identification guide

Cap gills and stem of Cystoderma jasonis


1.5 to 3.5cm across; initially convex, becoming broadly convex or flat, usually with a broad umbo; colour variable dark ochr to reddish brown; surface granular, sometimes radially wrinkled and often with a veil-fringed margin. In the cap context immediately below the pileipellis, rectangular asexual reproductive cells, known as arthroconidia or arthrospores, form as the mushroom matures.


4 to 7cm long and 4 to 8mm diameter; colour pale ochre above ring; ochre flushed lilac or purplish and smooth or very finely granular above ochraceous-cream ring zone, darker ochre and very scaly below.

Arthrospores, Cystoderma jasonis


The photomicrograph on the left shows arthroconidia 7-10 x 3.5-5μm in the cap context below the cuticle of Cystoderma jasonis.

Show larger image

Gills and stem of the Pine Powdercap


Adnate, crowded; white at first, becoming pale cream.


Spores, Cystoderma jasonis


Ellipsoidal to almond shaped, smooth, 6-7.5 x 3-4.5μm; amyloid.

Show larger image

Spore print


White or very pale cream.


Strong and unpleasant mouldy odour; no significant taste.

Habitat & Ecological role

Saprobic most commonly in conifer woodland on acid soil; occasionally on mossy acid heathland.


Summer and autumn.

Similar species

Cystoderma amianthinum is most often found in mossy acid grassland; is has no significant odour and its spores are shorter with a lower Q value (length to width ratio) than those of Cystoderma jasonis.

Culinary Notes

Cystoderma mushrooms are generally considered inedible, and there is speculation that at least some species in this genus may be toxic.

Reference Sources

Pat O'Reilly; Fascinated by Fungi, 2016.

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

British Mycological Society (2010). English Names for Fungi

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi.

Top of page...

Fascinated by Fungi, 2nd edn, hardback

Fascinated by Fungi. Back by popular demand, Pat O'Reilly's best-selling 450-page hardback book is available now. The latest second edition was republished with a sparkling new cover design in September 2022 by Coch-y-Bonddu Books. Full details and copies are available from the publisher's online bookshop...

© 1995 - 2024 First Nature: a not-for-profit volunteer-run resource

Please help to keep this free resource online...

Terms of use - Privacy policy - Disable cookies - Links policy