Leucanthemum lacustre (Brot.) Samp.

Perennials, 30–120(–200+) cm. Stems simple or distally branched. Basal leaves: petioles 30–60+ mm, expanding into lanceolate blades 50–100+ × 15–30+ mm, margins not lobed, usually toothed, sometimes entire. Cauline leaves ± petiolate or sessile; blades elliptic to oblanceolate, 30–120+ × 12–25(–35+) mm, margins of mid-stem leaves usually entire proximally, regularly serrate distally. Involucres (18–)25–35 mm diam. Phyllaries (the larger) 3–5 mm wide. Ray florets 21–34+; laminae 20–25(–35) mm. Ray cypselae 3–4 mm, apices usually auriculate adaxially. 2n = 198.

Chrysanthemum lacustre Brotero, Fl. Lusit. 1: 379. 1804