Major Groups > Gilled Mushrooms > Pale-Spored > Lactarius > Lactarius olympianus


Lactarius olympianus

[ Basidiomycota > Russulales > Russulaceae > Lactarius . . . ]

by Michael Kuo

Here is a gorgeous western Lactarius recognized by a combination of features:

  • a fairly large, bright orange cap with concentric zones of color;
  • growth under mountain spruces;
  • white milk that does not change color but stains the gills brownish to orangish brown;
  • a stem that lacks potholes and discolors brownish when handled;
  • acrid taste;
  • a cap margin that is not hairy, even when young; and
  • large, partially reticulate spores.

Lactarius olympianus is reminiscent of several other species in the "Lactarius zonarius" group, including the eastern, hardwood-associated Lactarius psammicola and the European species Lactarius zonarioides.


Ecology: Mycorrhizal with high-elevation spruces; summer and fall; Colorado to the Pacific Northwest. The illustrated and described collections are from Colorado.

Cap: 2-10 cm; convex with an incurved margin when young, becoming flat, shallowly depressed, or shallowly vase-shaped; slimy to sticky when wet; fairly bald; the margin not hairy, even when young; bright orange with concentric zones of paler orange.

Gills: Attached to the stem or running down it; close or nearly distant; whitish at first, becoming yellowish or orangish; developing orangish brown to brown stains and discolorations.

Stem: 2-5 cm long; up to 2 cm thick; more or less equal, or with a tapered base; dry or moist; without potholes; smooth; white; discoloring brownish to dingy orangish or yellowish where handled.

Flesh: White; not changing when sliced, or developing rusty stains.

Milk: White; not changing when exposed to air; staining the gills brownish to orangish brown.

Odor and Taste: Odor not distinctive; taste strongly acrid.

Chemical Reactions: KOH on cap surface negative.

Spore Print: Reported as creamy white.

Microscopic Features: Spores 7-10 x 8-11 µ; subglobose; ornamentation as amyloid warts and ridges 0.25-0.5 µ high, forming partial reticula. Pleuromacrocystidia not found. Cheilocystidia filiform to aciculate; to about 30 µ long. Pileipellis an ixocutis.

REFERENCES: Hesler & Smith, 1979. (Smith, Smith & Weber, 1979; Phillips, 1991/2005; Trudell & Ammirati, 2009; Evenson, 2015.) Herb. DBG 24276.

Thanks to the Sam Mitchel Herbarium of Fungi at the Denver Botanic Gardens for lending material for study.

Further Online Information:

Lactarius olympianus in Hesler & Smith (1979)
Lactarius olympianus at Roger's Mushrooms


Lactarius olympianus

Lactarius olympianus

© MushroomExpert.Com

Cite this page as:

Kuo, M. (2016, June). Lactarius olympianus. Retrieved from the MushroomExpert.Com Web site: