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Tansy ragwort Senicio jacoaea L. |
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Keys to Identification:
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Family: Asteraceae (Sunflower) Other Names: Stinking Willie, tansy butterweed USDA Code: SEJA Legal Status: Colorado Noxious Weed List A Identification Lifecycle: Biennial or short-lived perennial Growth form: Forb Flower: Yellow. July-September. Has both ray and disk flowers. Seeds/Fruit: Disk flowers are hairy. Ray flowers are smooth Leaves: 2-8 inches long. Multi-lobed Stems: Mature plants range from 1-6 feet in height. Stems have downy hairs. Roots: Taproot with fleshy side roots Similar Species Exotics: None known. Natives: Senicio sp., Grounsel Impacts Agricultural: Toxic to livestock Ecological: Displaces native vegetation Habitat and Distribution General requirements: Found in pastures, along rights-of- way and disturbed places. Prefers moist soils Distribution: Found in California, Idaho, Illinois, Maine, Massachusetts, Michigan, Montana, New Jersey, New York, Oregon, Pennsylvania, Washington. Recently found in Alaska. Not known to occur in Colorado. Historical: Tansy ragwort is native to Europe. Known in North America since the early 1900's. Biology/Ecology Life cycle: Tansy ragwort generally produces a basal rosette the first year, and flowers the following year. The plants are prolific bloomers and produce large quantities of seed from July through September. Mode of reproduction: Reproduces by seeds. May sprout from root fragments. Seed production: Produces up to 150,000 seeds. Seed bank: The majority of the seeds will germinate the following year, but some seeds may remain dormant for several years. Dispersal: Wind Integrated Management Summary As with other plants which reproduce primarily by seed, integrated management efforts must include the elimination of seed production and the depletion of the seed bank. Combine herbicide or mechanical removal of rosettes with removal of seed heads from any plants that have bolted. Apply herbicides at rosette to early bolt stages. References
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