Syn.: Sphaeria luteovirens Fr., Hypocrea luteovirens (Fr.) Fr., Peckiella luteovirens (Fr.) S. Imai, Byssonectria luteovirens (Fr.) Z. Moravec
Family: Hypocreaceae De Not.
Distribution: Evidently circumpolar range, documented throughout many parts of North America, western Europe to Ukraine, Kazachstan, Japan and Z. Moravec reports it from Czechia.
Ecology: Parasitic growth on Russula and occasionally on Lactarius. Common in wet weather wherever the host species are found.
Description: Stroma is yellow, then yellow and green, finally dark green, so dark that it becomes almost black. Then the white spores (fusiform, nearly smooth to verrucose and apiculate), shot out of the ostioles, can be seen on the dark background; perithecia dark green. Flesh of the host changes somewhat in consistency but it is firm and white.
Edibility: Not recommended because it is difficult to recognize the Russula species when the gills and spore print cannot be seen. It looks disgusting as well.
Notes: As it is not as conspicuous as Hypomyces lactifluorum, it is rarely seen.
There might be some confusion about validity of this species or Hypomyces viridis P. Karst., however, Index Fungorum recognizes both species as valid. H. viridis attacks gills and upper part of the stem and H. luteovirens eventually the whole fruiting body.
These images were taken in Canada, Alberta, Bragg Creek (summer 2013).
