Yarrow flowers (Achillea millefolium) 
Yarrow flowers (Achillea millefolium), a perennial plant of the Asteraceae family.
Characteristics
- It forms flat clusters of small white or pinkish flowers with an aromatic smell.
- It grows wild in meadows and along paths in temperate regions.
- In biodynamics it is the basis of preparation 502, encased in a stag's bladder.
Role in the preparation: The flower heads are picked in summer, dried and used as the recipe states.
Caution: Can cause skin reactions in people sensitive to Asteraceae: wear gloves.
Sources: Achillea millefolium - Wikipedia · Biodynamic agriculture - Wikipedia
Documentary information: this is neither a recommendation for use nor a plant-protection or veterinary claim. Check your country's regulations before any use.