Great Plains ragwort

Senecio tampicanus de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 6: 427. 1838; S. greggii Rydberg; S. imparipinnatus Klatt

Annuals, 20–50+ cm; taprooted (caudices ascending to erect). Stems 1 or 2–6+, clustered (bases cyanic), glabrous or leaf axils sparsely tomentose. Basal leaves (and proximal cauline) petiolate; blades oblanceolate to spatulate (usually pinnately lobed, lateral lobes 1–6+ pairs, their bases petioluliform, terminal lobes usually larger than laterals, often reniform to ± orbiculate, midribs sometimes ± winged and/or toothed between the primary lobes), 40–120+ × 10–30+ mm, bases ± cuneate, ultimate margins subentire or irregularly crenate, dentate, or lobed. Cauline leaves gradually reduced (± petiolate or sessile, clasping; often auriculate, pinnately dissected to pinnately lobed). Heads 4–25+ in corymbiform arrays. Peduncles bracteate, glabrous. Calyculi incon-spicuous or 0. Phyllaries 13 or 21, green (tips sometimes reddish), 3–7 mm, glabrous. Ray florets 8 or 13; corolla laminae 3–7 mm. Disc florets 30–45(–100+); corolla tubes 1.5–2.5 mm, limbs (1.5–)2.5–3.5 mm. Cypselae 1–1.5 mm, hirtellous on ribs; pappi 3–5 mm. 2n = 46.

Flowering Feb–Jun. Disturbed, wet, sandy or clay sites, roadsides, stream banks, waste areas; 0–1000 m; Ark., Kans., La., Okla., Tex.; Mexico.

Packera tampicana is fairly widespread along the Gulf Coastal Plain and north and in Mexico. Morphologically, P. tampicana most closely resembles P. glabella; the former grows in very wet, sandy or clay soils and open sunlight, the latter grows in drier habitats, usually in partial shade.