Appearance''Senecio vulgaris'' is an erect herbaceous annual growing up to 16 inches tall.:764 The inflorescences usually lack ray florets, the yellow disc florets mostly hidden by the bracts giving the flowers an inconspicuous appearance. ''Senecio vulgaris'' is very similar to ''Senecio viscosus'' but ''S. vulgaris'' does not have the glandular hairs and ray florets found in ''S. viscosus''.
⤷ In Latin ''Senecio'' means 'old man'. This name, used by Pliny, is in reference the plant becoming grey and hairy when fruiting.
⤷ ''Vulgaris'' means 'usual', 'common', or 'vulgar'.
⤷ Vernacular names for ''S. vulgaris'' in English include old-man-in-the-spring, common groundsel, groundsel, ragwort, grimsel, grinsel, grundsel, simson, birdseed, chickenweed, old-man-of-the-spring, squaw weed, grundy swallow, ground glutton and common butterweed.
Distribution''Senecio vulgaris'' is considered to be native to Europe, northern Asia, and parts of North Africa. Its further distribution is less clear. The United States Department of Agriculture , Natural Resources Conservation Service Plants Profile Database considers it to be native to all 50 of the United States of America, Canada, Greenland, Saint Pierre and Miquelon, the same USDA through the Germplasm Resources Information Network considers it to be native only to parts of Afro-Eurasia. The Integrated Taxonomic Information System Organization , a partnership among many United States federal government departments and agencies states that the species has been introduced to the 50 United States, and the online journal Flora of North America calls it "probably introduced" to areas north of Mexico. Individual research groups claim it is not native to areas they oversee: Florida, Washington, Wisconsin, Saskatchewan, British Columbia, Missouri. The United States Geological Survey reports that common groundsel is exotic to all 50 states and all Canadian provinces with the exception of Georgia, Kentucky, Massachusetts, and Labrador.
Habitat''Senecio vulgaris'' is a frost-resistant deciduous annual plant that grows in disturbed sites, waste places, roadsides, gardens, nurseries, orchards, vineyards, landscaped areas, agricultural lands, at altitudes up to 1,600 feet and is, additionally, self-pollinating producing 1,700 seeds per plant with three generations per year. Seeds are dispersed by wind and also cling to clothing and animal fur, and as contaminates of commercially exchanged seeds; the distribution of this plant throughout the world has been difficult if not impossible to contain.
DefenseIn the United States, ''Senecio vulgaris'' has been listed as a noxious weed, being both non-indigenous to most if not all of the Americas and having a reputation for being hepatotoxic to livestock and to humans.
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