Streambank Groundsel

Perennials, 20–70+ cm; fibrous-rooted (bases simple or branched, horizontal to erect). Stems usually 1, sometimes 2–4, clustered, glabrous or sparsely tomentose proximally. Basal leaves petiolate; blades usually broadly lanceolate to ovate, sometimes subhastate, 20–50+ × 20–40+ mm, bases truncate to subcordate or obtuse, margins crenate, denticulate, bluntly dentate, or sharply dentate (proximal cauline leaves petiolate; margins usually pinnately lobed to laciniate, sometimes subentire). Cauline leaves gradually reduced (becoming sessile, sometimes clasping). Heads 5–20+ in open or congested, subumbelliform arrays. Peduncles bracteate, glabrous. Calyculi inconspicuous. Phyllaries (13–)21(–30+), light green, 3–8 mm, glabrous. Ray florets 0, 8, or 13; corolla laminae 6–10+ mm. Disc florets 70–80+; corolla tubes 2.5–3.5 mm, limbs 2–3 mm. Cypselae 1–1.5 mm, glabrous; pappi 4.5–5.5 mm. 2n = 40, 44, 46, 80.

Senecio pseudaureus Rydberg, Bull. Torrey Bot. Club 24: 298. 1897