2. Senecio vulgaris L. (common groundsel)

Pl. 297 a, b; Map 1259

Plants more or less taprooted. Stems 8–40 cm long, when young with fine, woolly (cobwebby) hairs, sometimes becoming nearly glabrous with age, often reddish- or purplish-tinged. Basal and lower leaves 2–10 cm long, the blades narrowly elliptic to narrowly obovate, irregularly pinnately lobed, mostly bluntly pointed at the tip, tapered at the base to a poorly defined petiole, the margins otherwise irregularly few-toothed or with a few secondary lobes, sparsely to moderately pubescent with cobwebby hairs or scattered, minute, curled hairs. Upper leaves sessile, narrowly ovate to narrowly oblong-elliptic, mostly pinnately lobed, the margins irregularly few-toothed, wavy, or rarely with a few secondary lobes. Heads often somewhat nodding. Involucre 4–8 mm long, the inner bracts 18–22, green with minute, black tips, the outer series occasionally extending slightly down the stalk, linear, green with minute, black tips. Disc corollas 4–6 mm long. Ray florets absent. Fruits 2–3 mm long. 2n=40. April–May.

Introduced, uncommon and sporadic (native of Eurasia, introduced widely in North America). Greenhouses, gardens, railroads, and open, disturbed areas.

Most of the specimens until now have originated from the St. Louis metropolitan region. This species sometimes is spread as weeds in bedding plants. As such, it eventually may become established in other urban areas of the state.