Cirsium discolor
field thistle
Overview
Cirsium discolor is a native biennial thistle of eastern and central North America, growing 3-7 feet (0.9-2.1 m) tall on stout, branched, leafy stems from a deep taproot. In its first year it forms a rosette; in the second it bolts, flowers, sets seed, and dies. The deeply cut leaves are 3-8 inches (7.5-20 cm) long, green and lightly spiny above and densely white-woolly beneath, the two-toned surface behind the epithet discolor. From midsummer into fall, the stems are topped by flower heads 1-1.5 inches (2.5-4 cm) wide, packed with pink to lavender-purple disk florets above a spiny, cobwebby involucre. The species grows in prairies, old fields, woodland edges, and roadsides, supporting many insects: bees and butterflies take nectar, and goldfinches eat the seeds and line their nests with the seed down. Unlike several aggressive non-native thistles, this native species spreads only by seed and is far less weedy. Limitations include the spiny foliage, a tall and somewhat coarse form, and a short two-year life. Plants self-seed where the ground stays open, but rarely form dense stands.
Native Range
Cirsium discolor is native to eastern and central North America, from Quebec and the eastern United States west to the Great Plains. It grows in prairies, meadows, old fields, woodland edges, and along roadsides in full sun.Suggested Uses
Grown in prairie, meadow, and pollinator gardens and in restoration plantings for native habitat. Used at the back of naturalized borders where its height and spines suit a wilder planting. The seeds and nesting down support goldfinches in wildlife gardens.How to Identify
Appearance
Size & Dimensions
Height3' - 7'
Width/Spread1'6" - 3'
Reaches mature size in approximately 2 years
Bloom Information
Flower heads open from midsummer into fall, generally July through September. Each plant produces many heads in succession over several weeks, with pink to purple florets opening above the spiny involucre. Bees and butterflies visit through the bloom. Fluffy seed heads follow, releasing seeds on white down.
Detailed Descriptions
Flower Description
Pink to lavender-purpleFoliage Description
Green above, white-woolly beneathGrowing Conditions
Sun Requirements
Requires 6-10 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight