Distribution of ingenol derivatives in Euphorbia plants and UV-dependent promotion of ingenol production in greenhouse-grown Euphorbia plants

•Contents of total ingenol derivatives of 50 Euphorbia plants.•Existence of ingenol derivatives in Jatropha, Acalypha, Codiaeum, and Excoecaria.•Euphorbia tithymaloides 'Nanus' might be a better source for ingenol production.•Better greenhouse covering material for the production of ingenol derivatives.