Resinous substances may occur alone or in combination with essential oils or gums. Resins are unlike gums as they are insoluble in water, but they dissolve in other solvents including alcohol. Resin production occurs in various plants in nature, but only a few families are of commercial considerations. These include the Anacardiaceae (the sumac family), Burseraceae (the incense tree family), Cannabaceae (the hemp family), Dipterocarpaceae (major importance timber trade), Guttiferae (primarily tropical-some species offer resin which bees use in nest construction), Hammamelidaceae (the witch hazel family), Lamiaceae (mint family - culinary & essential oils), Leguminosae (the pea family), Liliaceae (the lily family), Meliaceae (the mahogany family), Pinaceae (the pine family of conifers), Styracaceae (the silver bells family - are evergreen or deciduous trees or shrubs) and Umbelliferae (the parsley family). The true botanical origin of a resin is often generally not definitive, especially in the case where they derive from fossil or semi fossil types.