Page authors: David Giblin, Don Knoke
Carduus tenuiflorus
slender flowered thistle, winged plumeless thistle
WTU specimens
Other herbaria

Distribution: Introduced in western WA; south to California and sparingly introduced in eastern U.S.

Habitat: Disturbed areas at low elevation

Flowers: June-July

Origin: Introduced

Conservation Status: Not of concern

Description:
General:

Erect annual, the stems 20-200 cm. tall, simple or openly branched, loosely white-woolly; wings from the leaf bases with teeth to 25 mm. long and spines to 15 mm. long.

Leaves:

Basal leaves tapered to winged petioles, the blades 10-25 cm. long, somewhat woolly on both surfaces, the margins pinnately 6-10 lobed; cauline leaves alternate, sessile, shorter and less divided.

Flowers:

Heads in tight clusters of 5-20 at the ends of stems, sessile, 15-22 mm. long and 7-12 mm. wide; involucral bracts linear-lanceolate, 2-2.5 mm. wide, mostly glabrous, with narrow scarious margins, the outer with spine tips 1-2 mm. long, the inner spineless; corollas pinkish, 10-14 mm. long, the lobes 1.5-2.5 times longer than the throat; pappus bristles 10-15 mm. long.

Fruits:

Achene brown, 4-5 mm. long.

Accepted Name:
Carduus tenuiflorus Curtis
Publication: Fl. Londin. 2(6,61): plate 55. 1789. 1789.

Synonyms & Misapplications:
Carduus pycnocephalus L. var. tenuiflorus (Curtis) Fiori
Additional Resources:

PNW Herbaria: Specimen records of Carduus tenuiflorus in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Carduus tenuiflorus checklist entry.

E-Flora BC: Carduus tenuiflorus atlas page.

CalPhotos: Carduus tenuiflorus photos.

USDA Plants: Carduus tenuiflorus information.

7 photographs:
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