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

21. Arnica discoidea Bentham, Pl. Hartw. 319. 1849.

Rayless arnica

Arnica alata Rydberg; A. cordifolia Hooker var. eradiata A. Gray; A. discoidea var. alata (Rydberg) Cronquist; A. discoidea var. eradiata (A. Gray) Cronquist; A. parviflora A. Gray

Plants 15–60 cm. Stems mostly simple or distally branched. Leaves 3–7 pairs, sometimes crowded at stem bases (basal leaves often persistent on sterile rosettes); petiolate (petioles narrow, 1.5–8 cm, often broadly winged on distal reduced leaves); blades usually ovate to broadly lanceolate, seldom subcordate, 2–12 × 1–7 cm, margins usually serrate to coarsely dentate or crenate, rarely subentire, faces glabrate to pilose, stipitate-glandular. Heads 3–10(–30; erect). Involucres turbinate-campanulate. Phyllaries 8–15, ovate-lanceolate to narrowly lanceolate. Ray florets usually 0 (corollas of peripheral florets rarely dilated, resembling rays). Disc florets 20–50; corollas yellow; anthers yellow. Cypselae dark gray, 6–8 mm, hirsute (hairs duplex) and stipitate-glandular; pappi white, bristles usually barbellate, sometimes subplumose. 2n = 38, 57, 76.

Flowering May–Jul. Chaparral, oak and pine forests; 100–1500 m; Calif., Nev., Oreg., Wash.


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