False mayweed

Matricaria maritima Linnaeus, Sp. Pl. 2: 891. 1753; Chamomilla maritima (Linnaeus) Rydberg

Perennials (sometimes biennials), 10–50(–80) cm. Stems 1–5+, usually procumbent, sometimes ascending (± erect), branched distally, glabrous or sparsely hairy. Leaf blades 2–8 cm, ultimate lobes ± cylindric, 4–20 mm, ± fleshy, apices obtuse or mucronate. Heads (3–)10–50 in corymbiform arrays or borne singly. Phyllaries centrally dark greenish or brownish, oblong to narrowly triangular or broadly triangular, unequal, scarious margins pale to dark brown or blackish brown, 0.2–1 mm wide. Ray florets 10–34+; corollas 10–16[–20] mm. Disc corollas ca. 2.5 mm. Cypselae pale to dark blackish brown, ribs ± contiguous or separated by less than ¹/4 their widths (1–2 supernumerary ribs sometimes present), abaxial-apical resin glands elongate (lengths 2+ times widths), abaxial faces transversely rugose, minutely roughened on faces and between ribs. 2n = 18, 36.

Subspecies 3 (2 in the flora): North America, Eurasia.