Richardson’s bitterweed, pingue rubberweed

Picradenia richardsonii Hooker, Fl. Bor.-Amer. 1: 317, plate 108. 1833 (as richardsoni)

Perennials, 7–34 cm (polycarpic; usually with highly branched woody caudices). Stems 1–20(–30+), usually green throughout, rarely purple-red-tinted proximally, branched distally, glabrous or ± hairy. Leaves: blades simple or lobed (lobes 3–7), glabrous or ± hairy, gland-dotted (basal leaf bases densely long-villous-woolly); mid leaves lobed (lobes 3–5, terminal lobes 0.7–2 mm wide). Heads 5–300+ per plant, in corymbiform arrays. Peduncles 1–5 cm, ± hairy. Involucres campanulate, 7–11 × 7–14 mm. Phyllaries in 2 series, unequal; outer 8–13, obovate to ovate to lanceolate, basally connate ¹/2 their lengths, 3.5–8 mm, apices acuminate to acute; inner 8–18, obovate, 3–8 mm, apices mucronate. Ray florets 7–14; corollas yellow, 7–17 × 3–6 mm. Disc florets 25–75+; corollas 3–5 mm. Cypselae narrowly obpyramidal, 2–3 mm; pappi of 4–8 obovate to lanceolate, aristate scales 1.8–3.5 mm. 2n = 30.

Varieties 2 (2 in the flora): w North America.