Field thistle

Cirsium discolor, the field thistle, is a biennial or short-lived perennial herb in the Asteraceae family native to eastern and central North America. It typically grows 1 to 2.5 metres tall on a stout, grooved, branching stem that arises in the second year from a deep taproot. The alternate leaves are deeply pinnately lobed with strongly spiny margins, dark green above and densely white-tomentose beneath, producing the distinctive bicoloured appearance that gives the species its specific epithet. Flower heads are large, solitary or in loose corymbs at branch tips, with phyllaries bearing weak spines and corollas ranging from pink-purple to occasionally white, blooming from mid summer into autumn. The achenes bear a plumose pappus of feathery, branched bristles that aids wind dispersal. Field thistle inhabits prairies, old fields, woodland edges, and disturbed open ground, and is an important nectar source for butterflies and goldfinches.