Images: ©Jouko Lehmuskallio
Sea Mayweed
Tripleurospermum maritimum
- Family: Daisy Family – Asteraceae (Compositae)
- Growing form: Biennial or perennial herb.
- Height: 10–60 cm (4–24 in.). Stems 1 to several, often tinged with red at the base.
- Flower: White strap-shaped ray-florets and yellow tubular disc-florets are grouped together into flower-like heads (capitula), 3–6 cm (1.2–2.4 in.) across. Corolla of 5 fused petals. Calyx rudimentary, no pappus present. Stamens 5, anthers united into a tube around the style. Pistil of 2 fused carpels, style solitary, stigma 2-lobed. Capitulum subtended by involucral bracts which are 1.5–5 mm (0.05–0.2 in.) wide and have a broad membranous margin.
- Leaves: Alternate. Basal leaves stalked, soon withering, stem leaves with very short stalk. Blade finely 2–3-pinnately lobed, feathery, somewhat fleshy.
- Fruit: A dark brown, flattened cypsela, with two oval, reddish or yellow oil glands.
- Habitat: Ssp. maritimum: Seashores. Ssp. subpolare: Cultivated land, roadsides, ditches, and waste ground. Ssp. phaeocephalum: Man-made habitats.
- Flowering time: June–September.
In Finland three sea mayweed subspecies, differing in their distribution and habitat preferences are recognized. Ssp. maritimum has fleshy leaf-blades with short lobes. The leaves of ssp. subpolare and ssp. phaeocephalum have longer lobes. In addition, there are differences in the width of the involucral bracts. Such differences also separate this species from its close relative, the scentless mayweed (T. inodorum). The bracts of the sea mayweed are 1.5–5 mm wide, those of the scentless mayweed do not exceed 1.5 mm. Furthermore, the number of white ray-florets differs. The sea mayweed has 20–35 ray-florets in each capitulum, the scentless mayweed rarely has more than 20.
