Chroogomphus // is a genus of mushrooms commonly known as pine-spikes or spike-caps based on their shape and because they are often found growing in association with pine trees. The genus is distributed throughout the Northern Hemisphere including North America, the Caribbean, Europe, and Asia.
These fungi are members of the family Gomphidiaceae which are agaricoid members of the Boletales (suborder Suillineae). Related to the genus Gomphidius (in which they were once classified), Chroogomphus are distinguished from Gomphidius by their lack of a partial veil.
Members of this genus have been thought to be ectomycorrhizal with various species of pine, however, there is now evidence that all members of the Gomphidiaceae are parasitic upon other boletes. Specifically, Chroogomphus species are thought to be parasitic on various conifer-associated Suillus species, with this parasitism often being highly species-specific. In the Pacific Northwest of North America, C. tomentosus is found with western hemlock (Tsuga heterophylla) and Douglas-fir (Pseudotsuga menziesii), while C. helveticus of Europe is found in conifer forests containing spruce (Picea ssp.).
Chroogomphus rutilus (image), found in Europe, is the type species for this genus. It has been the subject of investigation as the source of antibiotics, as well as other potentially useful secondary compounds.
The cap is up to 10 cm in diameter and red-brown in colour. The widely spaced gills are brownish-orange and decurrent with black to brownish-yellow spores. The stalk is brownish-yellow and tapers toward the base. The flesh is orange to salmon-coloured and turns violet when chewed.