Propolis

Resinous mixture made by honey bees from tree bud and bark exudates, beeswax and saliva.

Characteristics

Contains roughly 50 % plant resins and balsams and 30 % waxes.
Includes essential oils, pollen and phenolic compounds such as flavonoids.
Its composition and colour vary with region, plant sources and season.
Sticky at room temperature, it becomes hard and brittle when cold.

Role in the preparation: It is traditionally used as an alcoholic tincture, because its resins dissolve in alcohol rather than in water.

Caution: It can cause contact allergies in sensitive people: wear gloves, store it cool and away from light, and check local regulations before any use.

Sources: Propolis - Wikipedia · Propolis (bee glue) - British Beekeepers Association

Documentary information: this is neither a recommendation for use nor a plant-protection or veterinary claim. Check your country's regulations before any use.