Cirsium discolor aka Field Thistle

Cirsium discolor is known as field thistle or pasture thistle. It belongs to the daisy family, Asteraceae. Its native range covers central and eastern North America. This includes much of the eastern United States and southern Canada. It grows in prairies, pastures, old fields, and along roadsides. It also occurs in savannas and at woodland edges.

This upright plant lives as a biennial or short-lived perennial. It first forms a low rosette of leaves. Branched stems rise in its second year. Plants reach 3–10 feet (0.91–3.05 metres) tall. They spread 1–2 feet (0.30–0.61 metres) wide. Growth proceeds at a moderate pace. Most plants die after flowering, though some take longer to bloom. Green stems bear hairs but lack spines. The alternate leaves have deep, narrow lobes and sharp edges. White hairs cover their undersides. Leaves grow smaller toward the stem tips.

Flower heads form at the ends of the stems. Each head holds many small, tubular flowers. Their shades range from pink to purple, with rare white forms. Heads measure about 0.08–0.17 feet (0.025–0.051 metres) across. Green bracts surround them, each with a short spine. Bloom can extend from June through October. Chicago Botanic Garden lists July through October for its plants. Small brown fruits, called achenes, follow the flowers. Tufts of hair help the wind carry their seeds.

Full sun gives the best bloom, though plants accept some shade. They grow in clay, loam, or sand with good drainage. Sites can range from moist to dry. A deep taproot helps the plant withstand drought. Chicago Botanic Garden lists moderate water needs. Its hardiness range spans USDA zones 2–9. NC State lists zones 3–9. Plants spread through seed and need little routine care. Their short lives matter when planning a lasting planting.

Field thistle suits meadows, native gardens, and places left to naturalize. Small groups provide tall flowers and food for wildlife. Bees, beetles, and butterflies visit the nectar-rich heads. Finches and other songbirds eat the seeds. Native bees use the dead, hollow stems as nest sites. Leaving cut stems standing can preserve that shelter. Deer resistance adds value where browsing causes trouble. NC State reports no major pest or disease concerns. Sharp leaf spines can make handling awkward. The supplied sources give no food-use or toxicity assessment.