Senecio neomexicanus A. Gray in A. Gray et al., Syn. Fl. N. Amer. 1(2): 392. 1884 (as neo-mexicanus)

Perennials, biennials, or annuals, 20–50+ cm; fibrous-rooted, taprooted, or ± rhizomatous (bases branched, horizontal or ascending to erect). Stems 1 or 2–5+, clustered, lanate- or arachno-tomentose or glabrescent. Basal leaves (often abaxially cyanic) petiolate (petioles hairy to glabrate); blades ovate to lanceolate or narrowly lanceolate, 20–60+ × 10–30+ mm, bases abruptly contracted to tapering, margins subentire or denticulate to subserrate (abaxial faces usually tomentose, adaxials frequently glabrate). Cauline leaves gradually or abruptly reduced (proximal petiolate, similar to basals; mids and distals sessile, lanceolate, entire). Heads 3–20+ in open or compact, corymbiform to subumbelliform arrays (subtended by smaller arrays arising from leaf axils). Peduncles conspicuously bracteate, usually hairy. Calyculi conspicuous. Phyllaries 13 or 21, green or yellowish, 4–7+ mm, tomentose to glabrescent. Ray florets (5–)8 or 13; corolla laminae 4–10 mm. Disc florets 40–60+; corolla tubes 1.5–2.5 mm, limbs 3.5–4.5 mm. Cypselae 1.5–2.5 mm, usually hirtellous on ribs, sometimes glabrous; pappi 5–6+ mm. 2n = 44, 46, 92.

Varieties 3 (3 in the flora): w United States, w Mexico.