9. Cirsium vulgare (Savi) Ten. (bull thistle)

Pl. 254 i–k; Map 1058

Plants biennial, with a short, thickened taproot in addition to the fibrous roots. Stems 40–200 cm long, usually well branched, sparsely to moderately pubescent with cobwebby hairs, often nearly glabrous toward the base, with sometimes-narrow, spiny-margined wings, at least above the midpoint. Basal leaves 10–40 cm long, 3–15 cm wide, narrowly elliptic to oblanceolate, rarely obovate, more or less tapered at the base, mostly narrowly angled at the tip, with several shallow to deep lobes, the margins otherwise coarsely lobed or toothed and spiny, the upper surface appearing green, strongly roughened with numerous short, stiff, spinelike or barblike bristles, not cobwebby-hairy, the undersurface thinly or finely pubescent with cobwebby hairs. Stem leaves progressively reduced from near the stem base, the main leaves 3–15 cm long, with deep (more than 1/2 of the way from the margin to midrib), narrow lobes, slightly clasping and long-decurrent (more than 1 cm), otherwise like the basal leaves. Heads usually relatively numerous, solitary or in loose clusters at the branch tips, appearing sessile or very short-stalked. Involucre 25–40 mm long, as long as or slightly longer than wide (often appearing broader when pressed or at fruiting), somewhat cobwebby-hairy, the lower and median bracts tapered to a spreading, spiny tip, this 2–5 mm long, straw-colored to light yellow, rarely also slightly sticky along the midrib. Corollas 25–35 mm long, reddish purple to purple, the lobes 5–7 mm long. Pappus 20–28 mm long, white or light tan. Fruits 3.0–4.5 mm long. 2n=68. June–September.

Introduced, widely scattered in Missouri (native of Europe, Asia, introduced throughout the U.S., Canada). Upland prairies and openings of disturbed, mesic to dry upland forests; also pastures, railroads, roadsides, and open, disturbed areas.