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Non-Native Plant Species of Alaska Bull thistle Cirsium vulgare (Savi) Ten. Synonyms: Carduus lanceolatus L, Carduus vularis Savi, Cirsium lanceolatum (L.) Scop. Other common names: common thistle, spear thistle Family: Asteraceae (Compositae) Description Bull thistle is a biennial with a short, fleshy taproot. The stem is 2 to 5 feet tall, conspicuously winged, bearing many spreading branches. It is green or brownish, and sparsely hairy. Leaves are pinnately lobed, hairy and prickly on upper side and cottony underneath. Leaf blades extend down petiole and along stem, forming long, prickly wings. Flowerheads are one to two inches wide with deep purple flowers. The bristles on the pappus are feathery (Hultén 1968, Whitson et al. 2000). This is the only large-headed thistle with a prickly, winged stem. Ecological Impact Impact on community composition, structure, and interactions: Bull thistle competes with native species for water, nutrients, and space; displacing native species, and decreasing forage sites for grazing animals. Impact on ecosystem process: Unknown. Biology and Invasive Potential Reproductive potential: Bull thistle reproduces only by seeds. Cross-pollination is required to set fertile seed; a wide variety of insects pollinate bull thistle. Average fruit production is nearly 4,000 per plant. Seeds viability is high and up to 90% may germinate within a year. No persistent seedbank is known (Klinkhamer and De Jong 1988). Role of disturbance in establishment: Disturbance of soil and vegetation increases greatly seedling emergence and establishment of bull thistle. Potential for long-distance dispersal: Most seeds fall within three feet of the parent plant, but up to 10 percent may travel distances with little wind (Klinkhamer et al. 1988). Potential to be spread by human activity: This species can be spread by the movement of livestock, vehicles, farm machines, and seed and hay. Germination requirements: Germination is stimulated by soil moisture and light. Seed germinate well over a wide range of temperatures. Seeds have no innate dormancy; germination is mostly in the spring. Growth requirements: Bull thistle is most common on soil with intermediate moisture. It tolerates a wide range of soil pH. Listing: Noxious weed in Colorado, Iowa, Kansas, Maryland, Michigan, Minnesota, New Mexico, Oregon, Pennsylvania, and Washington; in Manitoba and Ontario (USDA 2002). Distribution and Abundance Bull thistle is most common in recently or repeatedly disturbed areas such as pastures, rangelands, along roads and ditches. However, it can also colonize areas in relatively undisturbed grasslands, meadows, and forest openings. continent except Antarctica. It probably was introduced to North America as a contaminant in seed or ballast in the late 1800s. South Coastal Interior- Boreal Arctic-Alpine Collection Site Distribution of bull thistle in Alaska. Native and current distribution: Native to Europe, western Asia, and northern Africa, it is now naturalized and widespread throughout the United States and southern Canada and on every other References: Hultén, E. 1968. Flora of Alaska and Neighboring Territories. Stanford University Press, Stanford, CA. 1008 pp. Klinkhamer, P. G., T. J. De Jong. 1988. The importance of small-scale disturbance for seedling establishment in Cirsium vulgare and Cynoglossum officinale. J. of Ecology. 76:383-392. Klinkhamer, P. G., T. J. De Jong, E.van der Meijen. 1988. Production, dispersal and predation of seeds in the biennial Cirsium vulgare. J. of Ecology. 76:403-414. USDA (United States Department of Agriculture), NRCS (Natural Resource Conservation Management This species does not withstand cultivation. Mechanical cutting of plants at the soil surface is an effective method of control. Control programs should be maintained for at least 4 years. Additionally, it is relatively easily controlled with herbicides. Two USDA approved insects have been successful in California. A variety of natural seed predators are present in The Netherlands (unknown if present in North America) (Klinkhamer et al. 1988). Service). 2002. The PLANTS Database, Version 3.5 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 708744490 USA. Whitson, T. D., L. C. Burrill, S. A. Dewey, D. W. Cudney, B. E. Nelson, R. D. Lee, R. Parker. 2000. Weeds of the West. The Western Society of Weed Science in cooperation with the Western United States Land Grant Universities, Cooperative Extension Services. University of Wyoming. Laramie, Wyoming. 630 pp. Alaska Natural Heritage Program Environment and Natural Resources Institute University of Alaska Anchorage 707 A Street, Anchorage, Alaska 99501 Phone (907) 257-2780 Fax (907) 257-2789 Last Updated May 3, 2006