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FNA | Family List | FNA Vol. 21 | Asteraceae | Hymenoxys

8. Hymenoxys richardsonii (Hooker) Cockerell, Bull. Torrey Bot. Club. 31: 468. 1904.

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.


1 Stems 1–10; leaves ± hairy; heads 5–35+ per plant; involucres 8–11 × 9–14 mm; outer phyllaries 9–13, weakly to moderately keeled; ray corollas 11–17 mm   8a Hymenoxys richardsonii var. richardsonii
+ Stems (2–)5–20(–30+); leaves glabrous or sparsely hairy; heads (30–)80–250(–300+) per plant; involucres 7–8 × 7–9 mm; outer phyllaries 8–9, strongly keeled; ray corollas 7–11 mm   8b Hymenoxys richardsonii var. floribunda


 

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