Ragwort n. : A name given to several species of the composite genus Senecio.

Example:
How do i know if my horse has Ragwort poisining?

Taxonomy
Senecio, 03-06, Ragwort, species, groundsel, Brettell, unranked, Golden Ragwort, Jeffrey, Plants, Search, genus, free encyclopedia, Flora, Asteraceae, Synonyms, Succulent, marsh ragwort.

Defination from the web:
ragwort. Senecio vaginatus. Senecio vernalis — Eastern groundsel. Senecio viscosus — sticky ragwort ... Golden Ragwort" (HTML). Connecticut Wildflowers. http://www.ct-botanical-society.org/galleries/packeraaure.html. ...