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2.0 NOXIOUS WEED MANAGEMENT CRITERIA <br />2.1 EXISITNG VEGETATION <br />The existing vegetation in the subject area was observed for the state listed noxious weeds and <br />listed weeds of concern for Colorado (see Appendix A) and the local weeds of concern listed for <br />Larimer County (see Appendix B). The existing vegetation at the quarry consists of big and little <br />bluestem, blue grama and side -oats grama grasses with mountain mahogany and ponderosa <br />pine. <br />2.2 NOXIOUS WEEDS IN THE STUDY AREA <br />The field observation revealed one (1) recorded noxious weed of concern from the species <br />listed on Colorado's top ten prioritized weed species (Appendix A, #24), Diffuse Knapweed. The <br />same noxious weed is listed in Larimer County Weed List (Appendix B). <br />2.2.1 Diffuse Knapweed - Plant Biology: the diffuse knapweed is a tap -rooted annual, <br />biennial or short-lived perennial forb that reproduces by seed. As a deep rooted weed that <br />invades disturbed and undisturbed grassland, shrublands and rangelands, it will outcompete <br />native species. It does not tolerate cultivation and is generally not found in cultivated lands or <br />irrigated pastures. Usually diffuse knapweed is found on light, dry, porous soils. It typically <br />grows 6 to 24 inches tall and consists of a single main stem divided into numerous branches <br />about halfway up the stem, giving it a ball -shaped appearance and tumbleweed mobility. Each <br />branch produces a single flower head. Flowers are usually white, but occasionally light purple. <br />Bracts on diffuse knapweed have a rigid terminal spine about 1/4 to 1/3 inch long with four to <br />five pairs of shorter lateral spines. Bracts can have dark -colored tip but lack the dark fringe <br />present on spotted knapweed. Plants form rosettes that resemble spotted knapweed. Bolting <br />occurs in early summer, and plants bloom from mid -summer to early fall'. <br />2 <br />