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Tansy Ragwort (Senecio jacobaea)       

Tansy Ragwort flowers.
Tansy Ragwort flowers.

Tansy Ragwort can be found along road sides and waste grounds, and grows in all cool and high rainfall areas. It is native to the Eurasian continent. In Europe it is widely spread, from Scandinavia to the Mediterranean. In Britain it is listed as a weed. In the USA it has been introduced, and is present mainly in the North West and North East: California, Idaho, Illinois, Maine, Massachusetts, Michigan, Montana, New Jersey, New York, Oregon, Pennsylvania, and Washington.

The plant is biennual or short-lived perennial. The stems are erect, straight, have no or few hairs, and can reach a height of 6 feet. The leaves are pinnately lobed and the end lobe is blunt. The hermaphrodite flower heads are 1 inch wide, and are borne in dense, flat-topped clusters; the florets are bright yellow. It has a long flowering period lasting from June to November.

Pollination is by a wide range of bees, flies and moths and butterflies. Over a season, one plant may produce 2,000 to 2,500 yellow flowers in 20- to 60-headed, flat-topped corymbs. This number of seeds produced may be as large as 75,000 to 200,000, although in its native range in Eurasia very few of these would grow into new plants and research has shown that most seeds do not travel a great distance from the parent plant. (From Wikipedia)

Tansy Ragwort rosette.
Tansy Ragwort rosette.

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