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   Yellow Starthistle Centaurea solstitialis   Rosette Rosette leaves are deeply lobed and could be confused with dandelion. Adult Yellow starthistle is a two to three foot tall winter annual with blue-green coloration. Flower Flowers are yellow. Cream-colored thorns, one-quarter to three-quarter inches long, protrude from the flowering heads. Bloom is in early summer. Weed Infestation Yellow starthistle was introduced from Europe. It grows well on dry sites in rangeland, roadsides, and waste areas. It can cause "Chewing disease" in horses that consume it. Winged Stem Stems are sparsely leaved and heavily ridged. Tap Root 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