Bull Thistle spreads by seeds. The middle and upper stems of large plants with narrow, very spiny leaf-like wings running lengthwise. Bull thistle (Cirsium vulgare):Common in Clackamas County, moderately invasive, see our weed profile Biennial; Stems are leafy, stout, branched, and somewhat woolly; Flower heads are large, rose to purple with many sharp spine-tipped bracts The flowering stems elongate and flower in the second year. top. It forms occasional side stems, but remains erect in stature, reaching 3-6' in height. The heads of purple Flowering stems reach 2-5 ft in height. https://www.canr.msu.edu/resources/bull-thistle-cirsium-vulgare Bull thistle is a weed that can grow in a wide range of environments but prefers disturbed areas. They are in rosette stage in the first year and flower and set seeds in the second year. Bull Thistle has a two year life span. The plants die after flowering or after the first frost of that second year. Bull Thistle Cirsium vulgare Aster family (Asteraceae) Description: This plant is an obligatory biennial that forms a rosette of leaves during the first year, and bolts upward during the second year to produce flowers. Life Cycle. Musk thistle (Carduus nutans) is a 3- to 8-foot biennial thistle. Other Names: Life Cycle: Biennial Description: The bull thistle is primarily a pasture weed having spiny-winged stems and leaves. Reproduction: By seed . Musk Thistle. The leaves have rough hairs on the upper surface and soft hairs on the lower. Biennial. Thistles can be found growing in many locations--lawns, garden beds, along the roadside, and in pastures and fields. The tip of each of the lobes of the bull thistle has a long, yellow spine. The seeds of this weed are short-lived on the soils surface but can lay dormant in the soil for many years. This broadleaf weed has a fleshy taproot the first year, and then a fibrous root system forms the second year. It likes pastures, edges of woods, waste places, fence lines and roadsides. About Bull Thistle: The Bull Thistle is a biennial weed that reproduces by the wind blowing their seeds. Bull thistle reaches a height of from 2 to 6 feet. The hairy, prickly leaves overwinter to develop stems and branches of up to 2 feet in spring. The flowering stems elongate and flower in the second year. Basal rosette forms the first year. It is often confused with musk thistle, which usually lacks the leaf hairs. Bolts, flowers, and dies in the second year. Propagation. Reproducing only by seed. Leaf margins are toothed with sharp spines. Seeds germinate rapidly and are spread by wind. In summer the plant grows a scented flower that resembles a spiny globe topped with fringed pink petals. Stems. It tends to grow best in soils with intermediate moisture although it will grow in dry and wet soils. As a biennial, bull thistle has a two‐year life cycle. Weedy characteristics: Bull thistle is highly competitive and aggressive, and forms dense colonies that choke out native vegetation important to wildlife and pollinators. Stems are erect, 30-150 cm high but rarely much taller, usually widely branched and short-hairy. Bull thistle starts life as a spiny leaved rosette. Life cycle: Biennial. It has a deep taproot, which makes manual pulling a challenge. The plants die after flowering or after the first frost. top. Bull thistle has a biennial (two-year) life cycle. Flowers are dark pink to purple with spined bracts. Plants grow vegetatively their first year as rosettes of green, sparsely hairy leaves. Life Cycle. Bull Thistle leaves grow alternate from each other and form a rosette. Plants grow vegetatively their first year as rosettes of green, prickly, sparsely hairy leaves. Forms occasional side stems, but remains erect in stature, reaching 3-6 ' in height the... 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