Arnica maritima Linnaeus, Sp. Pl. 2: 884. 1753, not Senecio maritimus Linnaeus f., 1782; S. pseudoarnica var. rollandii Victorin; S. rollandii (Victorin) Victorin

Perennials, (15–)20–60(–100) cm (caudices erect). Herbage arachno-tomentose to sericeous-lanate (especially on abaxial faces of phyllaries), unevenly glabrescent. Stems single (turgid). Leaves evenly distributed (proximal withering before flowering); subsessile or petiolate; blades obovate to oblanceolate, 5–15(–25) × 2–6(–10) cm, bases tapered, margins serrate-dentate to denticulate or subentire (distal leaves slightly smaller). Heads 1–5(–15+) in corymbiform arrays (involucres notably large, 20–40 mm diam.). Calyculi of 6–10 linear bractlets (longest nearly equaling phyllaries). Phyllaries ± 21, 8–15 mm (sometimes purplish or pinkish-tinged), tips greenish. Ray florets usually ± 21, rarely 0; corolla laminae 20–25 mm. Cypselae glabrous. 2n = 40.

Flowering summer. Sandy-gravelly ocean shores and upper beaches; 0 m; St. Pierre and Miquelon; B.C., N.B., Nfld. and Labr., N.S., Que.; Alaska, Maine; ne Asia.

Rayless individuals of Senecio pseudoarnica have been recognized as var. rollandii or forma rollandii (Victorin) Fernald; they are not otherwise distinctive.