Russula cerolens — Pocket-stalked russula

Pocket-stalked russula, Russula cerolens

Pocket-stalked russula2, photograph by Benjamin Woo with permission from University of Washington, Burke Museum.

Pocket-stalked russula, Russula cerolens

Young specimens of pocket-stalked russula6, photograph by Benjamin Woo with permission from University of Washington, Burke Museum.

Pocket-stalked russula, Russula cerolens

Pocket-stalked russula sliced to show hollow chambers in stem, photograph by Ludovic Le Renard.

Pocket-stalked russula, Russula cerolens

Russula cerolens spores7 sketch by Benjamin Woo with permission from University of Washington, Burke Museum.

Unknown, likely poisonous

Gills: Narrowly attached, white to light cream
Spore print: White

Odour: Mild to unpleasant, described as burnt hair or burnt plastic, or a soft French cheese.
Cap: 3–10 cm in diameter and viscid (slimy) when wet. The shape is rounded when young, flat when old, and the center is depressed. The margin has radial grooves. The colour is light yellow-brown to middle coffee-brown, sometimes with greenish tints. As in other Russula species, the flesh of the cap, gills and stem is fragile.
Gills: White to cream, almost free, barely touching the stem. Each gill extends from the stem to the cap margin without shorter spacer gills (lamellulae).
Stem: 3–8 cm long x 1–2 cm wide, straight and white. Often staining orange-brown at the base. White inside. Not solid but with 2–4 hollow chambers that give the pocket-stalked russula its common name. Not fibrous; the stem breaks with a snap rather than bending.
Ring or veil: None.
Cup: None.
Spores: 5.5–8.5 x 4.5–7 µm with warts and a network of ridges connecting the warts.
Habitat: In all kinds of forests, ectomycorrhizal with oaks (Quercus), pines (Pinus), and spruce (Picea).
Geographic distribution: Western North America, from British Columbia in the north to southern California.

Russula cerolens is common but has usually been misidentified in BC and the Pacific northwest. It belongs to a group of species with brown to yellow-brown caps, chambered stems, and a distinct zone of radial grooves near the cap margin. The European name Russula amoenolens has been used for this species.

No reports of poisoning, perhaps because its unpleasant odour discourages its consumption. It may be mildly toxic4.

Treatment: Contact your regional Poison Control Centre if you or someone you know is ill after eating russulas. Poison Centres provide free, expert medical advice 24 hours a day, seven days a week. If possible, save the mushrooms or some of the leftover food containing the mushrooms to help confirm identification.

Poison Control:
British Columbia: 604-682-5050 or 1-800-567-8911.
United States (WA, OR, ID): 1-800-222-1222.

1
MyCoPortal. Mycology Collections Portal, <http://mycoportal.org/portal/collections/harvestparams.php> accessed February 2018.
2
Specimen Russula cerolens WTU-F-038535, GenBank #KX813574.
3
Bazzicalupo, A. L. et al. Troubles with mycorrhizal mushroom identification where morphological differentiation lags behind barcode sequence divergence. Taxon 66, 791-810, doi:10.12705/664.1 (2017).
4
Siegel, N. & Schwarz, C. Mushrooms of the Redwood Coast. A Comprehensive Guide to the Fungi of Coastal Northern California. Ten Speed Press, Berkeley, California (2016).
5
Shaffer, R. L. North American Russulas of subsection Foetentinae. Mycologia 64, 1008-1053, doi:10.2307/3758072 (1972).
6
Specimen Russula cerolens WTU-F-038942, GenBank #KX813449.
7
Specimen Russula cerolens WTU-F-039347, GenBank #KX813233.