Tansy ragwort and groundsels
Senecio jacobaea (Jacobaea vulgaris), Senecio spp.
- Plant type
- forb
- Settings
- Disturbed ground, Rangeland
- Risk
- Moderate risk Our rating from the cited sources.
- Review
- Not yet reviewed by a veterinarian.
Photos
Planned.
How to tell it
Heads of yellow flowers with a ring of green bracts underneath; first-year plants form a low rosette (Merck, ARS).
Look-alikes: Planned.
What to do on a site walk
- Limit time and rotate.
- Never feed hay containing it.
Why it matters
- Toxic principle
- Pyrrolizidine alkaloids
- Toxic parts
- Whole plant; rosette highest
- Basis for our rating
- Chewgrass rating. ARS: most toxic to cattle and horses; sheep and goats are used to graze it down. Cornell lists goats.
Signs in goats
Liver damage that shows up weeks to months later: weight loss, diarrhea or straining, belly swelling, aimless wandering (ARS).
If you think an animal has been poisoned, call your vet right away.
Season
Rosette stage most toxic; stays toxic in hay (ARS).
Sources
- USDA ARS Poisonous Plant Research Lab: Tansy Ragwort
- Second source (poisonousplants.ansci.cornell.edu)
Links last checked: 2026-10-31