Clematis spp. (ERGOT); an ascomycetous fungus which grows on small grain (e.g., rye); also contains the alkaloid indole. Yellow Starthistle 65. According to Dr. Harris Steinman, an allergy expert from South Africa, "Russian thistle can cause dermatitis in persons who come into direct contact with it. Cirsium arvense (CANADA THISTLE); plant may contain toxic levels of nitrates. It is native throughout Europe and northern Asia, and widely introduced elsewhere. Managing Canada Thistle Canada thistle (Cirsium arvense) is a perennial that has plagued farmers in America since European settlement, and is a Noxious Weed in Pennsylvania. NebGuide: Canada thistle (CIAR4) OK-OSU Extension-Thistles and their Identification (CIAR4) Ohio State University: Identifying noxious weeds (CIAR4) Purdue University: Control practices for Canada thistle (CIAR4) The Nature Conservancy: Wildland Weeds Management & Research Program (CIAR4) UC Davis, IPM: abstract & images (CIAR4) The Canada thistle is a perennial species of flowering plant in the Asteraceae family. A note on "safe" plants: The plants on this list are generally believed to be safe.However, if you suspect that a child (or adult) has eaten quantities of any of these plants (or any of their parts), or if you notice symptoms such as illness or dermatitis after handling these plants, call your Poison Control Center for additional information: (800) 222-1222. Dalmatian Toadflax 46. It is adapted to a wide range of soil conditions, and spreads vigorously by wind-borne seeds and by way of its extensive, creeping root system. Canada Thistle 42. Spotted Knapweed 80. Scientific Name: Cirsium arvense (L.) Scop (ITIS) Common Name: Canada thistle, Californian thistle, Canadian thistle, creeping thistle, field thistle, corn thistle, perennial thistle, field thistle. This highly invasive thistle prevents the coexistence of other plant species through shading, competition for soil resources and possibly through the release of chemical toxins poisonous to other plants. Leafy Spurge 59. This thistle is also commonly known as the creeping thistle and field thistle. Combining control methods is the best form of Canada thistle management. Ontario Weeds Act - noxious; Other provinces - noxious in AB, BC, SK, MB, and QC; Canadian Federal Seeds Act - Class 3 ; U.S. Federal Noxious Weed - no Claviceps spp. Current Status. The dermatitis appears to be due only to mechanical irritation from plant floral bracts, which pierce the skin and stimulate an urticarial reaction." Hoary Cress 55. 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