Pasture Thistle

Flowers of Cirsium pumilum are reportedly sweetly scented.

Biennials or monocarpic perennials, 25–100 cm; sometimes perennating by root sprouts. Stems erect, villous with septate trichomes and sometimes thinly arachnoid tomentose; branches 0–few, distal, ascending. Leaves: blades oblong-elliptic, 5–30+ × 2–10 cm, ± undulate, shallowly to deeply pinnatifid, lobes ovate to broadly triangular, usually separated by broad sinuses, spinose-dentate or lobed, main spines 1.5–7 mm, slender to stout, abaxial faces villous with septate trichomes, at least along veins, sometimes thinly arachnoid, adaxial faces villous with septate trichomes and thinly arachnoid tomentose or subglabrous; basal often present at flowering, bases tapered; principal cauline sessile, moderately reduced distally, bases often auriculate-clasping; distal reduced, similar to proximal. Heads 1–few, borne singly at tips of main stem and branches, often closely subtended by 1–several bracts. Peduncles 0–15+ cm (above distal leaves. , leafy-bracted. Involucres broadly cylindric to ovoid, 3.5–5 cm, 2.5–3 cm diam. (appearing much wider and hemispheric to campanulate in pressed specimens), loosely arachnoid on phyllary margins or glabrate. Phyllaries in 8–10 series, imbricate, ovate or lanceolate (outer) to lance-linear (inner), abaxial faces with ± prominent glutinous ridge, outer and middle appressed, apices ascending to spreading, spines 1.5–6 mm; apices of middle and inner narrowed and scabrid-denticulate, innermost spineless, tapered and entire or with expanded, erose-denticulate, flexuous tips. Corollas pink to purple (white), 40–60 mm, tubes 20–35 mm, throats 11–15 mm, lobes 7–10 mm; style tips 3–7 mm. Cypselae stramineous to brown, 3.5–5 mm, apical collars yellow or colored like body; pappi 35–45 mm. 2n = 30.

Carduus pumilus Nuttall, Gen. N. Amer. Pl. 2: 130. 1818

Cirsium pumilum, the pasture thistle, is a North American species of plants in the tribe Cardueae within the family Asteraceae. The species is native to the northeastern and north-central United States as well as to the Canadian Province of Ontario.

Cirsium pumilum is a biennial or perennial herb up to 100 cm (40 inches) tall, blooming once before dying. It has leaf blades up to 30 cm (12 inches) long, with slender to stout spines. There are usually a few flower heads, sweetly scented, with pink, purple or white disc florets but no ray florets.

Varieties Cirsium pumilum var. hillii (Canby) B. Boivin - Great Lakes region, upper Mississippi Valley Cirsium pumilum var. pumilum - northeastern + east-central United States from Maine to South Carolina west to Ohio