Infected Mushroom

Lobster Claw Mushroom
Lobster Fungus infecting a mushroom


Documenting Local Biodivesity: Lobster Fungus

The orange coating on the mushroom above is a parasitic ascomycete named Hypomyces lactifluorum and commonly called “lobster fungus” because its reddish-orange color resembles a boiled lobster. It is infecting a species of Lactarius or Russula but the lobster fungus has completely covered its host and identification is not so simple. In the immediate area I saw Russula emetica, R. brevipes, and a Clitocybe species.

The fungus Hypomyces lactifluorum parasitizes Lactaria and Russula species, reportedly only white ones, covering the entire mushroom with a red coating of thousands of tiny bumps which are the spore producing bodies. The mushrooms normally have round and flat to slightly convex caps but when infected become deformed and twisted. Even the gills are deformed and all that remains are thick smooth ridges. As the parasite also infects the interior of the mushroom the texture is changed from brittle to solid.

The flavor of the mushroom also changes and is reported to be nutty or even like bacon. I have not tried this fungus infected mushroom and do not recommend eating it because the host species are members of the genera Russula and Lactarius which have both edible and poisonous species. When completely engulfed by the lobster fungus it becomes difficult to identify the host species.


Russula brevipes, one of the host species to lobster fungus
Russula brevipes, one of the host species to lobster fungus


Species of Lactarius and Russula are ectomycorrhizal fungi growing in association with trees such as pines, spruces, and oaks. Hypomyces lactifluorum parasitizes these mushrooms and is thus an indirect parasite on the trees although no species of Hypomyces are known to infect trees. In this way the lobster fungus behaves like some flowering plants such as ghost pipe (Monotropa uniflora) and coral-root orchids (Corallorhiza spp.). These plants engage in myco-heterotrophy and obtain all products of photosynthesis by parasitizing the ectomycorrhizal fungi that grow in association with the roots of trees. Interestingly, Monotropa and Corallorhiza associate with Russula and Lactarius fungus species.

References consulted

Agerer, R. (2001). Exploration types of ectomycorrhizae. Mycorrhiza 11:107–114.

Marx, D. H. (1969). Ectomycorrhizae as Biological Deterrents to Pathogenic Root Infections in Proceedings of the First North American Conference on Mycorrhizae, April 1969. Misc. Publication 1189. U.S. Department of Agriculture – Forest Service.

Miller, O. K. (1981). Mushrooms of North America. E. P. Dutton, New York, Chanticleer Press Edition.

Rochon, C. (2007). Ecophysiology of the Chanterelle and the Lobster Mushroom in Eastern Canadian Jack Pine Forests. Presentation at the 10th North American Congress of Agroforestry, Quebec.

Rochon, C.; Paré, D.; Khasa, D.P.; Fortin, J.A. (2009). Ecology and management of the lobster mushroom in an eastern Canadian jack pine stand. Canadian Journal of Forest Research 39(11): 2080-2091.

Tedersoo, L.; May, T. W.; and Smith, W. E. (2010). Ectomycorrhizal lifestyle in fungi: global diversity, distribution, and evolution of phylogenetic lineages. Mycorrhiza 20:217–263.

Yang, S. and Pfister, D. H. (2006). Monotropa uniflora plants of eastern Massachusetts form mycorrhizae with a diversity of russulacean fungi. Mycologia. 98:535–540.

Zimmer, K.; Meyer, C.; Gebauer, G. (2008). The ectomycorrhizal specialist orchid Corallorhiza trifida is a partial myco-heterotroph. New Phytologist 178:395–400.

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