Senecio is a genus of flowering plants in the daisy family (Asteraceae) that includes groundsels and some ragworts. Variously circumscribed taxonomically, the genus Senecio is one of the largest genera of flowering plants. Plants of the World Online currently accepts 1482 species.
Description
Senecio squalidus flowerheads have the yellow ray florets typical of many species
The flower heads are often rayed (though the type species Senecio vulgaris does not have ray florets), with the heads borne in branched clusters, and usually completely yellow, but green, purple, white and blue flowers are known as well.
In its current circumscription, the genus contains species that are annual or perennial herbs, shrubs, small trees, aquatics or climbers.
Pyrrolizidine alkaloids are found in all Senecio species. These alkaloids serve as a natural biocides to deter or even kill animals that would eat them. Livestock generally do not find them palatable. Senecio species are used as food plants by the larvae of some Lepidoptera species that have developed tolerance for these alkaloids.
Morphology
Senecio squalidus flowerheads have the yellow ray florets typical of many species
The flower heads are often rayed (though the type species Senecio vulgaris does not have ray florets), with the heads borne in branched clusters, and usually completely yellow, but green, purple, white and blue flowers are known as well.
In its current circumscription, the genus contains species that are annual or perennial herbs, shrubs, small trees, aquatics or climbers.
