Leucanthemum lacustre

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.

Flowering spring-summer. Disturbed places, meadows, seeps, clearings; 0-50 m; introduced; Calif.; Europe (Portugal).