Distribution, ecology, and immunosuppressive properties of Tricholoma populinum (Basidiomycetes).

Tricholoma populinum is widely distributed in Europe and North America. In the GDR 110 localities have been recorded, ranging from sea level to 470 m s.m. It is associated with many Populus spp. on acidic and neutral ground; its frequency has locally increased by recultivation of slap-dumps and waste land with poplars. Maximum of fructification is in the first decade of October. Investigations, stimulated by empiric observations on immunosuppressive effects of the mushroom in allergic diseases of man, lead to isolation of ergosterol peroxide as one substance responsible for these effects.