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   Russian Knapweed Centaurea repens   Rosette Basal leaves are lobed and are two to four inches in length. Adult A perennial, Russian knapweed grows two to three feet tall. Flower It has pinkish flowers. Bloom is early summer through late summer. Weed Infestation Russian knapweed is native to Eurasia. It infests rangelands, field edges, pasture, roadsides, and other disturbed soils. Knapweed's release chemical substances into the soil that inhibit the growth of competing vegetation. It can cause "Chewing disease" in horses that consume it. Tap Root Roots may go eight feet deep or more. Flower Bract Flower bracts have membranous cream-colored tips. 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