Gomphus clavatus is a threatened fungus forming mycorrhiza with coniferous trees and beech in mature forests on calcareous, loamy soils and clay. The extent of these forest types is declining mainly due to cutting of oldgrowth forests and apparent difficulties to re-establish after clear cutting. It is red-listed in 17 European countries.
It is a highly appreciated edible mushroom. Picking of fruiting bodies does not affect the survival of a mycelia or its ability to produce fruiting coming years.
Aronsson G. 2006. Species Action Program for Gomphus clavatus (in Swedish, with English summary) Åtgärdsprogram för bevarande av violgubbe (Gomphus clavatus). Naturvårdsverket. Rapport 5638. Can be freely downloaded at http://www.naturvardsverket.se/Documents/publikationer/620-5638-7.pdf
Dahlberg A & Croneborg H. 2003. 33 threatened fungi in Europe. Complementary and revised information on candidates for listing in Appendix I of the Bern Convention T-PVS (2001) 34 rev 2.
Lange, L. 1974. The distribution of macromycetes in Europe. Dansk Botanisk Arkiv 30(1).