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Rangeland-Pasture Recommendations <br /> Scotch thistle Identification and <br /> Management <br /> Scotch thistle (Onopordum acanthium) is a non-native biennial forb that <br /> reproduces solely by seed. A biennial is a plant that completes its lifecycle within <br /> two years. During the first year of growth, Scotch thistle appears as a rosette in <br /> spring or fall. During the second year in mid to late spring - the stem bolts, <br /> flowers, sets seed, and the plant dies. A prolific seed producer,Scotch thistle can <br /> produce up to 14,000 seeds per plant. Therefore, the key to managing this plant is <br /> to prevent seed production. <br /> Scotch thistle can grow up to 12 feet tall. Stems are numerous, branched, <br /> and have broad, spiny wings. The leaves are large, green, spiny, and covered <br /> with fine dense hair giving the leaf a woolly appearance. The flowers are violet <br /> to reddish in color, numerous (70-100/plant), and are surrounded by spine- <br /> tipped bracts. You can expect to see flowers from mid-June to September. <br /> � a <br /> E - <br /> V i r <br /> � �� f Yk .�R�Hp .L,d.'�� fit•� �,[.♦. <br /> Due to the robust, spiny nature of Scotch thistle, this plant can act as a <br /> living barbed wire fence, making areas impassible for wildlife, livestock, and <br /> people. Scotch thistle invades rangeland, overgrazed pastures, roadsides, and <br /> irrigation ditches. It also prefers moist areas adjacent to creeks and rivers. <br /> On the backside of this sheet are Scotch thistle management <br /> recommendations. If you have any questions, please contact the Weld County <br /> Public Works Dept.,Weed Division at(970) 304-6496 ext. 3770. Please visit our <br /> website www.weldweeds.org. <br />