Bermudagrass Johnsongrass Medusahead Quackgrass Field Bindweed Hoary Cress Diffuse Knapweed Russian Knapweed Spotted Knapweed Squarrose Knapweed Purple Loosestrife Perennial Pepperweed Leafy Spurge Yellow Starthsitle Canada Thistle Musk Thistle Scotch Thistle Dyer's Woad Back to main weeds page   Diffuse Knapweed Centaurea diffusa   Rosette Leaves have finely divided lobes. Adult It is an annual or a short-lived perennial averaging one to two feet tall. Flower Flowers are white to rose in color. Diffuse knapweed differs from squarrose knapweed in that toothed flower bracts are straight rather than arched outward. It blooms throughout summer. Weed Infestation Native to Eurasia, diffuse knapweed inhabits dry rangeland, roadsides, field edges, and waste areas. Knapweed's release chemical substances into the soil that inhibit the growth of competing vegetation. Back to main weeds page   Buffalobur Common Burdock Camelthorn Goatsrue Jointed Goatgrass Poison Hemlock Black Henbane Houndstongue Blue-Flowering Lettuce Western Whorled Milkweed Silverleaf Nightshade Yellow Nutsedge Puncturevine Russian-Olive Saltcedar St. Johnswort Bull Thistle Dalmatian Toadflax Yellow Toadflax Velvetleaf