Cirsium purpuratum

Cirsium purpuratum is a thistle in the daisy family, Asteraceae. It comes from Honshu, Japan, including the island’s central region. It grows on mountain slopes with sand, gravel, or rocks. Recorded habitats lie between 1,969 and 5,249 feet [600–1,600 metres]. This short-lived herbaceous perennial forms clumps and loses its leaves seasonally. It is not native to Britain or Ireland.

Garden plants reach about 1.6–3.3 feet [0.5–1 metre] tall. Their spread falls within the same range. They take about two to five years to reach full size. Dark green leaves have deep lobes and sharp spines. The largest leaves grow at the base of the plant. These can reach about 2.3 feet [0.7 metres] long. Leaves become smaller farther up the stems. The large basal leaves give the clump a bold outline.

Large flower heads hang down in late summer. Each head holds many fine florets in shades of pink-purple. Spiny bracts bend back around the flower heads. Soft, fluffy seed heads follow the blooms. Gardeners can leave these heads when they want seed. Otherwise, they can remove the spent flowers. The leaves and flower heads both bring strong shapes to beds. The RHS suggests this plant for informal and wildlife gardens.

Choose full sun and soil that drains well. Suitable soils include sand, loam, and chalk. The plant accepts acid, neutral, and alkaline conditions. It suits sandy banks, gravel beds, and scree gardens. Both exposed and sheltered sites can meet its needs. South-facing and west-facing spots match the RHS guidance. Moisture can range from dry to moist, provided drainage stays good. The RHS assigns it hardiness rating H7. This covers winter lows below −20°C. Grow new plants from seed or divide established clumps. Divide them in autumn or early spring. Pests rarely cause problems, though powdery mildew can occur.

Plants For A Future lists the cooked root as edible. The root is slender and shaped like a carrot. That source suggests it may contain much inulin. People cannot digest this substance, and gut fermentation may cause gas. Its food-use rating is low, at one out of five. The same source reports no known hazards or medicinal uses. That hazard entry does not establish safety for pets.