Burke: Carduus pycnocephalus

	Carduus pycnocephalus
	Italian plumeless thistle
Habit	Annuals, 20-200 cm in total height, stems simple to openly branched, loosely tomentose with fine single-celled hairs and sessile growths with curled, septate hairs; teeth of wings up to 10 mm, wing spines to 20 mm.
Leaves	Basal leaves tapering to winged petioles, blades 10–25 cm, margins pinnately 2 to 5 lobed, abaxial faces ± tomentose, adaxial faces tomentose and pilose, often glabrate; cauline leaves sessile, shorter, margins less divided than basal, distally reduced to bracts.
Flowers	Heads borne singly or clustered in tight groups of 2-5, heads at ends of branches and sometimes in upper axils, sessile or short-pedunculate, 20–25 mm; peduncles winged throughout or unwinged, 0–2 cm long, tomentose; involucres cylindric to ellipsoid, 17–22 mm diameter; phyllaries linear to lanceolate, with appressed loosely tomentose bases, 2–3 mm wide and ascending, linear appendages 0.5–1.5 mm wide, not scarious, distally scabrous on midribs and margins, spine tips 1–3 mm, inner straight and erect, with unarmed or minutely armed tips; Corollas purple, dark purple, or pink, 14–16 mm long tube; lobes 3 times longer than throat.
Fruit	Cypselae ellipsoid, golden to brown, 4–6 mm, finely 20-nerved; pappus bristles 15–20 mm.

	Carduus pycnocephalus
Flowering time	June-July
Habitat	Disturbed, open areas at low elevation.
Distribution	Occurring west of the Cascades crest in Washington, where known only from Clallam County; Washington to California and Idaho, also in central and eastern U.S. [WildflowerSearch map] [BONAP county map]
Origin	Introduced from Europe
Conservation status	Not of concern
Sibling taxa	C. acanthoides, C. nutans, C. tenuiflorus
Subordinate taxa	C. pycnocephalus ssp. pycnocephalus
Web links	Local floras: OR, WA Local Web sites: Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Carduus pycnocephalus

Italian plumeless thistle

Habit

Annuals, 20-200 cm in total height, stems simple to openly branched, loosely tomentose with fine single-celled hairs and sessile growths with curled, septate hairs; teeth of wings up to 10 mm, wing spines to 20 mm.

Leaves

Basal leaves tapering to winged petioles, blades 10–25 cm, margins pinnately 2 to 5 lobed, abaxial faces ± tomentose, adaxial faces tomentose and pilose, often glabrate;

cauline leaves sessile, shorter, margins less divided than basal, distally reduced to bracts.

Flowers

Heads borne singly or clustered in tight groups of 2-5, heads at ends of branches and sometimes in upper axils, sessile or short-pedunculate, 20–25 mm;

peduncles winged throughout or unwinged, 0–2 cm long, tomentose;

involucres cylindric to ellipsoid, 17–22 mm diameter;

phyllaries linear to lanceolate, with appressed loosely tomentose bases, 2–3 mm wide and ascending, linear appendages 0.5–1.5 mm wide, not scarious, distally scabrous on midribs and margins, spine tips 1–3 mm, inner straight and erect, with unarmed or minutely armed tips;

Corollas purple, dark purple, or pink, 14–16 mm long tube;

lobes 3 times longer than throat.

Fruit

Cypselae ellipsoid, golden to brown, 4–6 mm, finely 20-nerved;

pappus bristles 15–20 mm.

Carduus pycnocephalus

Flowering time

June-July

Habitat

Disturbed, open areas at low elevation.

Distribution

Occurring west of the Cascades crest in Washington, where known only from Clallam County; Washington to California and Idaho, also in central and eastern U.S.

[WildflowerSearch map]

[BONAP county map]

Origin

Introduced from Europe

Conservation status

Not of concern

Sibling taxa

C. acanthoides, C. nutans, C. tenuiflorus

Subordinate taxa

C. pycnocephalus ssp. pycnocephalus

Web links